Introductory Chemistry, 2nd Edition Nivaldo Tro

Btec , Biology dept, Guangdong institute of Education

Chemistry for Biology

Chapter 3ChemicalEquilibrium2009, Bio-department

Thermodynamics: Directionality of Chemical Reactions

Ludwig Boltzmann 1844-1906.Famous for his equation statistically defining entropy.Josian W. Gibbs 1839-1903.Pioneered concepts of chemical thermodynamics and free energy.

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1

1

1

1

So far, we have tried to answer the following questions:(1) What are the energetics (heat) of a reaction? Is it exothermic (H= -) or endothermic (H= +)?(2) How fast (kinetics) and how (mechanism) does the reaction go? (3) To what extent does it go? (equilibrium)(4) Does it go, i.e., is it spontaneous? This is the subject of this chapter.And finally now ..

Spontaneous processes: defined descriptively as a processthat occurs by itself (and the reverse does not occur by itself)The opposite:

is not spontaneous,but, it is possible (how does a refrigerator work?).Other spontaneous processes (ask yourself: does reverse ever occur by itself?)nail rustingeggs breaking (Humpty Dumpty)paper burningwater freezing at -10oCice melting at +10oCgases mixheatheatis spontaneous,

All of these spontaneous processes are also described as: irreversibleThere are reversible processes, but the systems must be at equilibrium. heat + ice water at +10oCSpontaneous, irreversibleheat + ice water at -10oCSpontaneous, irreversibleheat + ice water at 0oC Reversible; equilibriumBoth ice and water coexist at 0oCEither process, or can occur at equilibriumIrreversibility Spontaneity

What makes a process spontaneous (irreversible)?Exothermic reactions tend to be spontaneous(exception, dissolving ammonium salts),and increasing entropy (randomness) tends to causeprocesses to be spontaneous; but overallGibbs Free Energy must decrease in orderfor a process to be spontaneous.G

examples:Ice melting similar to gas expansion more randomness and disorder, even though process is endothermicInk drops in water ink becomes evenly distributed in water; increase in randomness and disorder.Decay of biological organisms increase in randomness and disorder.Dissolving of salts in water increase in randomness and disorderTo Summarize: what contributes to spontaneity?1. Exothermic processes (heat is evolved).2. Any process which increases randomness and disorder.

The thermodynamic quantity which describes randomness and disorder is called ENTROPY and denoted as SThe SECOND LAW OF THERMODYNAMICS postulates the existence of entropy; it also states that the entropy of the universe is constantly increasing. It is not a conserved quantity.Gases have more entropy than liquids, which have more entropy than solids.Corollary: Melting, or vaporization, increases entropy.Corollary: In a chemical rx., increasing the number of moles of a gas, increases the entropy (e.g.,

H2O(g) H2(g) + O2(g)).4. Dissolving or mixing increases entropy.5. Corollary: precipitation decreases entropy.6. Increasing the temperature increases entropy.

Thermodynamic CalculationsWhat is G for the oxidation of SO2 to SO3 at 25C? Is the reaction spontaneous? exothermic?

SO2(g) + O2(g) SO3(g)Hf -296.8 0 -395.2 H = -98.4 kJS 0.2485 (0.205) 0.2562 S = -0.0948 kJ

G = H TS = -98.4 (298)(-0.0948) = -98.4 + 28.2 = -70.15 kJ The reaction is spontaneous. The reaction is exothermic.Note: Be sure you convert S values from J to kJ

What is G for the decarboxylation of limestone at 25C? Is the reaction spontaneous? exothermic?

CaCO3(s) CaO(s) + CO2(g)Hf -1207.1 -635.5 -393.5 H = +178.1 kJS 0.0929 0.0398 0.2136 S = +0.1605 kJ

G = H TS = +178.1 (298)(+0.1605) = + 178.1 - 47.83 = +130.27 The reaction is not spontaneous. The reaction is endothermic.Note: Be sure you convert S values from J to kJ

How do we make the decarboxylation of limestone spontaneous?

Set G = 0, the the crossing over point where the reaction converts from nonspontaneous to spontaneous.

G = 0 = H TS 0 = +178.1 T(+0.1605) T = 1109K = 837

When the temperature falls below 837C, CO2 begins spontaneously to react with CaO to form CaCO3: CaO(s) + CO2(g) CaCO3(s) At room temperature, G = + 130.27 kJ

Calculate the boiling point of methanol.

CH3OH(l) CH3OH(g) Hf -238.7 -200.7 H = +38.0 kJ S +0.1268 +0.2398 S = +0.113 kJ

At equilibrium, G is always 0. G = 0 = H TS =+38.0 T(+0.113) Tb = 336K = 63.3Note: Be sure you convert S values from J to kJ

Additional aspects of Free EnergyEven though a reaction has a negative G it may occur too slowly to be observed (i.e. combustion).Thermodynamics gives us the direction of a spontaneous process, it does not give us the rate of the process.A nonspontaneous process can be driven if coupled with a spontaneous process this is very important in life processes (i.e., respiration to form ATP), and can be used in industrial processes, such as smelting. To calculate K values, use G = -RT ln Keq.

This refers to the G difference of the standard states of compounds, before equilibrium is attained.

Laws of Thermodynamics1st Law. Energy is neither created nor destroyed. In chemistry, chemical energy can be converted into heat and vice versa.2nd Law. Entropy increases spontaneous; i.e., the natural tendency is for randomization.3rd Law. The entropy of a perfect crystal at 0K is zero (it is impossible to attain 0K).

*Reaction RatesSome chemical reactions proceed rapidly.

Like the precipitation reactions where the products form practically the instant the two solutions are mixed.Other reactions proceed slowly.

Like the decomposition of dye molecules of a sofa placed in front of a window.The rate of a reaction is measured in the amount of reactant that changes into product in a given period of time.

Generally moles of reactant used per second.Like miles per hour.Chemists study ways of controlling reaction rates.

*Reaction Rates, ContinuedInitially, only reactants are presentAfter 15 seconds, the left reaction is 60% complete, but the right reaction is only 20% completeAfter 30 seconds, the left reaction is complete,whereas the right reaction is only 40% done.After 45 seconds, the right reaction is still not complete

*2 N2O5 (g) 4 NO2(g) + O2(g)Over time, theconcentrations of reactants decreaseas products increase.

Decomp of N2O5

Time (sec)Dt (sec)[N2O5] (M)-D[N2O5]Rate, -D[N2O5]/Dt[O2], MD[O2]Rate, D[O2]/Dt[NO2], MD[NO2]Rate, D[NO2]/DtLn[N2O5]0/[N2O5]1/[N2O5]-1/[N2O5]0

02.3300.0000.0000.000.00

11100111002.0800.2501.13E-050.1250.1251.13E-050.5000.5004.50E-050.110.05

1920081001.9100.1701.05E-050.2100.0851.05E-050.8400.3404.20E-050.200.09

31600124001.6700.2409.68E-060.3300.1209.68E-061.3200.4803.87E-050.330.17

52400208001.3500.3207.69E-060.4900.1607.69E-061.9600.6403.08E-050.550.31

72000196001.1100.2406.12E-060.6100.1206.12E-062.4400.4802.45E-050.740.47

112700407000.7200.3904.79E-060.8050.1954.79E-063.2200.7801.92E-051.170.96

138900262000.5500.1703.24E-060.8900.0853.24E-063.5600.3401.30E-051.441.39

188600497000.3400.2102.11E-060.9950.1052.11E-063.9800.4208.45E-061.922.51

Time (sec)Dt (sec)P(N2O5) (torr)-DP(N2O5)Rate, DP(N2O5)/DtP(O2)DP(O2)Rate, DP(O2)/DtP(NO2)DP(NO2)Rate, DP(NO2)/Dt

0348.400

6006002471018.45E-0251518.45E-02203202.8003.38E-01

1200600185625.17E-0282315.17E-02327124.0002.07E-01

1800600140453.75E-02104233.75E-0241790.0001.50E-01

2400600105352.92E-02122182.92E-0248770.0001.17E-01

300060078272.25E-02135142.25E-0254154.0009.00E-02

360060058201.67E-02145101.67E-0258140.0006.67E-02

420060044141.17E-0215271.17E-0260928.0004.67E-02

480060033119.17E-0315869.17E-0363122.0003.67E-02

54006002497.50E-0316257.50E-0364918.0003.00E-02

60006001865.00E-0316535.00E-0366112.0002.00E-02

720012001083.33E-0316943.33E-0367716.0001.33E-02

84001200552.08E-0317232.08E-0368710.0008.33E-03

96001200328.33E-0417318.33E-046914.0003.33E-03

[N2O5], M[NO2], M[O2] (M)Rate (M/sec)Rate/[N2O5] (1/sec)k (L-mol-1-sec-1)Temp(K)1/T (1/K)ln{k (L-mol-1-sec-1)}

2.212.001.001.14E-055.16E-064.8E-043183.14E-03-7.64

2.211.002.001.12E-055.07E-068.8E-043233.10E-03-7.04

2.210.000.001.13E-055.11E-061.6E-033283.05E-03-6.44

2.000.000.001.05E-055.25E-062.8E-033333.00E-03-5.88

1.790.000.009.67E-065.40E-06

1.510.000.007.83E-065.19E-06

1.230.000.006.31E-065.13E-06

0.920.000.004.81E-065.23E-06

&CKinetics - 8

Decomposition of N2O5 at 45C

2 N2O5 4 NO2 + O2

Decompostion of N2O5 at 45CDependence of Initial Rate on N2O5 Concentration

Rate Dependence on Temperature

Conc vs Time

2.3300

2.080.1250.5

1.910.210.84

1.670.331.32

1.350.491.96

1.110.612.44

0.720.8053.22

0.550.893.56

0.340.9953.98

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[N2O5] (M)

[O2], M

[NO2], M

Time, sec

Concentration, M

Decomposition of N2O5 at 45 C

Rate vs Time Chart

0

0.0000112613

0.0000104938

0.0000096774

0.0000076923

0.0000061224

0.0000047912

0.0000032443

0.0000021127

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y = (10-5)e(0.000009x)

Rate, -D[N2O5]/Dt

Time, sec

Rate, D[]/Dsec

Decomposition of N2O5 @ 45C

Log Chart

0

0.1135003739

0.1987650255

0.3330446411

0.5457636751

0.7415082523

1.1743723345

1.4437052683

1.9246779289

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y= 10-5x

Ln[N2O5]0/[N2O5]

Time, sec

Ln[N2O5]0/[N2O5]


Inverse Chart

0

0.0515846814

0.0943756601

0.1696178459

0.3115561914

0.4717163515

0.9597043395

1.3889972688

2.5119919212

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1/[N2O5]-1/[N2O5]0

Time, sec

1/[N2O5] - 1/[N2O5]0


Activation Energy

-7.6417244541

-7.0355886505

-6.4377516497

-5.8781358618

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ln{k (L-mol-1-sec-1)}

1/T, (1/K)

ln k, L/molsec

Determining Activation Energy, ln k vs 1/T

Decomp of H2O2

Decomposition of H2O2(aq) at 40C

2 H2O2 2 H2O + O2

Time (sec)Dt (sec)[H2O2] (M)-D[H2O2] (M)Rate, -D[H2O2]/Dt (M/sec)Ln[H2O2]0/[H2O2]1/[H2O2]-1/[H2O2]0

01.0000.000.00

21600216000.5000.5000.00001157410.691.00

43200216000.2500.2500.0000057871.393.00

64800216000.1250.1250.00000289352.087.00

86400216000.0630.0630.00000144682.7715.00

k (sec-1)T (K)1/T, (1/K)Ln(k), (1/sec)

2.19E-115000.002000-24.545

6.92E+0110000.0010004.237

1.02E+0615000.00066713.835

1.23E+0820000.00050018.628

Conc vs Time, H2O2

1

0.5

0.25

0.125

0.0625

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[H2O2] (M)

Time, sec

Concentration, M

Decomposition of Hydrogen Peroxide

Log & Inverse, H2O2

00

0.69314718061

1.38629436113

2.07944154177

2.772588722215

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Ln[H2O2]0/[H2O2]

1/[H2O2]-1/[H2O2]0

Time, sec

Concentration Function


Act. En., H2O2

-24.5445344791

4.2370008626

13.8353131853

18.6276949133

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Ln(k), (1/sec)

1/Temp, (1/K)

Ln k, (1/sec)

Activation Energy for Decomposition of Hydrogen Peroxide

Disprop. of BrO

Time (sec)Dt (sec)[BrO-1] (M)-D[BrO-1] (M)Rate, 1/3-D[BrO-1]/Dt (M/sec)-Ln[BrO-1]1/[BrO-1]

00.7500.28771.3333333333

10100.5280.2227.33E-030.63871.8939393939

20100.4080.1203.96E-030.89652.4509803922

30100.3320.0762.51E-031.10263.0120481928

40100.2800.0521.72E-031.27303.5714285714

50100.2420.0381.25E-031.41884.132231405

60100.2130.0299.57E-041.54654.6948356808

70100.1900.0237.59E-041.66075.2631578947

80100.1720.0185.94E-041.76035.8139534884

90100.1570.0154.95E-041.85156.3694267516

100100.1440.0134.29E-041.93796.9444444444

[BrO3-1], MD[BrO3-1]Rate, D[BrO3-1]/Dt (M/sec)

0.0000

0.07330.07337.33E-03

0.11290.03963.96E-03

0.13790.02512.51E-03

0.15510.01721.72E-03

0.16760.01251.25E-03

0.17720.00969.57E-04

0.18480.00767.59E-04

0.19070.00595.94E-04

0.19570.00494.95E-04

0.20000.00434.29E-04

[Br-1], MD[Br-1]Rate, 1/2 D[Br-1]/Dt (M/sec)

0.0000

0.14870.14877.44E-03

0.22910.08044.02E-03

0.28010.05092.55E-03

0.31490.03481.74E-03

0.34040.02551.27E-03

0.35980.01949.72E-04

0.37520.01547.70E-04

0.38730.01216.03E-04

0.39730.01005.02E-04

0.40600.00874.36E-04

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Disproportionation of Hypobromite Ion3 BrO-1 BrO3-1 + 2 Br-1

Conc vs Time, BrO

0.75

0.528

0.408

0.332

0.28

0.242

0.213

0.19

0.172

0.157

0.144

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[BrO-1] (M)

Time, sec

Concentration of BrO-1, M

Disproportionation of Hypobromite

Log & Inverse, BrO

0.28768207251.3333333333

0.63865899531.8939393939

0.89648810462.4509803922

1.10262031013.0120481928

1.27296567583.5714285714

1.41881755284.132231405

1.54646311334.6948356808

1.66073120685.2631578947

1.76026080225.8139534884

1.85150947366.3694267516

1.93794197946.9444444444

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-Ln[BrO-1]

1/[BrO-1]

Time, sec

Concentraiton Function


HCN + H2O

Time (sec)Dt (sec)[HCN] (M)-D[HCN] (M)Rate, -D[HCN]/Dt (M/sec)[NH4HCO2], MD[NH4HCO2]Rate, D[NH4HCO2]/Dt (M/sec)

00.10000.0000

2.00E+052.00E+050.09840.00168.00E-090.00160.00168.00E-09

5.00E+053.00E+050.09610.00237.67E-090.00390.00237.67E-09

1.00E+065.00E+050.09230.00387.60E-090.00770.00387.60E-09

2.00E+061.00E+060.08510.00727.20E-090.01490.00727.20E-09

3.00E+061.00E+060.07850.00666.60E-090.02150.00666.60E-09

4.00E+061.00E+060.07240.00616.10E-090.02760.00616.10E-09

5.00E+061.00E+060.06680.00565.60E-090.03320.00565.60E-09

6.00E+061.00E+060.06170.00515.10E-090.03830.00515.10E-09

7.00E+061.00E+060.05690.00484.80E-090.04310.00484.80E-09

8.00E+061.00E+060.05250.00444.40E-090.04750.00444.40E-09

9.00E+061.00E+060.04840.00414.10E-090.05160.00414.10E-09

1.00E+071.00E+060.04470.00373.70E-090.05530.00373.70E-09

2.00E+071.00E+070.01990.02482.48E-090.08010.02482.48E-09

3.00E+071.00E+070.00890.01101.10E-090.09110.01101.10E-09

4.00E+071.00E+070.00400.00494.90E-100.09600.00494.90E-10

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HCN(aq) + H2O(l) NH4HCO2(aq)

HCN + H2O

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

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[HCN] (M)

[NH4HCO2], M

Time (sec)

Concentration, M

HCN + H2O NH4HCO2

CH3Cl + H2O

Time (sec)Dt (sec)[CH3Cl] (M)-D[CH3Cl] (M)Rate, -D[CH3Cl]/Dt (M/sec)[CH3OH], MD[CH3OH]Rate, D[CH3OH]/Dt (M/sec)[HCl], MD[HCl]Rate, D[HCl]/Dt (M/sec)

00.10000.00000.0000

40400.08230.01771.46E-040.01770.01774.43E-040.01770.01774.43E-04

80400.06780.01451.20E-040.03220.01453.63E-040.03220.01453.63E-04

120400.05580.01209.90E-050.04420.01203.00E-040.04420.01203.00E-04

160400.04600.00988.09E-050.05400.00982.45E-040.05400.00982.45E-04

200400.03780.00826.77E-050.06220.00822.05E-040.06220.00822.05E-04

240400.03110.00675.53E-050.06890.00671.68E-040.06890.00671.68E-04

280400.02560.00554.54E-050.07440.00551.38E-040.07440.00551.38E-04

320400.02110.00453.71E-050.07890.00451.13E-040.07890.00451.13E-04

360400.01740.00373.05E-050.08260.00379.25E-050.08260.00379.25E-05

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Hydrolysis of CH3Cl@ 90CCH3Cl + H2O CH3OH + HCl

CO + NO2

Time (sec)Dt (sec)[CO], (M)-D[CO], (M)[NO2], (M)-D[NO2], (M)Rate, -D[CO]/Dt, (M/sec)

00.1000.100

10100.0670.0330.0670.0333.30E-03

20100.0500.0170.0500.0171.70E-03

30100.0400.0100.0400.0101.00E-03

40100.0330.0070.0330.0077.00E-04

100600.0170.0160.0170.0162.67E-04

10009000.0020.0150.0020.0151.67E-05

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Oxidation of CO by NO2

CO(g) + NO2(g) CO2(g) + NO(g)

CH3OH + HCl

Time (sec)Dt (sec)pH[H+1], (M)[HCl], M-D[HCl]Rate, D[HCl]/Dt (M/sec)Ln[HCl]0/[HCl]1/[HCl] - 1/[HCl]0Time (sec)Dt (sec)[SO2Cl2], (M)-D[SO2Cl2], (M)Rate, -D[SO2Cl2]/Dt, (M/sec)ln[SO2Cl2]0/[SO2Cl2]1/[SO2Cl2]

0-0.271.861.860.0000.00001.00E-020.0000

8080-0.221.661.660.202.53E-030.1150.06620209.70E-033.00E-041.50E-050.0303

15979-0.181.511.510.151.85E-030.2070.12450309.28E-034.20E-041.40E-050.0758

314155-0.121.321.320.201.26E-030.3450.222100508.61E-036.70E-041.34E-050.15016

628314-0.01001.021.020.299.39E-040.5990.4402001007.41E-031.20E-031.20E-050.30035

4002005.49E-031.92E-039.60E-060.60082

7003003.50E-031.99E-036.63E-061.050186

10003002.30E-031.20E-034.00E-061.470335

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Nucleophilic Substitution

CH3OH(aq) + HCl(aq) CH3Cl(aq) + H2O(l)

Decomposition of SO2Cl2@ 320CSO2Cl2 SO2 + Cl2

CH3OH + HCl

0

0

0

0

0

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[HCl], M

Time (sec)

[HCl], M

Nucleophilic Substitution CH3OH(aq) + HCl(aq) CH3Cl(aq) + H2O(l)

Sheet8

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[SO2Cl2], (M)

Time (sec)

[SO2Cl2], M

Decomposition of SO2Cl2 @ 325CSO2Cl2 SO2 + Cl2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

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1/[SO2Cl2]

Time (sec)

1/[SO2Cl2] - 1/[SO2Cl2]0

Decompostion of SO2Cl2, 1/[SO2Cl2] vs Time

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

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ln[SO2Cl2]0/[SO2Cl2]

Time (sec)

Ln[SO2Cl2]0/[SO2Cl2]

Decompositon of SO2Cl2, Ln[SO2Cl2] vs Time

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

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Ln[HCl]0/[HCl]

Time (sec)

Ln[HCl]0/[HCl]

Nucleophilic Substitution, CH3OH + HCl, Ln[HCl] vs Time

0

0

0

0

0

0

0

0

0

0

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1/[HCl] - 1/[HCl]0

Time (sec)

1/[HCl] - 1/[HCl]0

Nucleophilic Substitution, CH3OH + HCl, 1/[HCl] vs time

0

0

0

0

0

0

0

0

0

0

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Sheet10

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Sheet11

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Sheet12

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Sheet13

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Sheet14

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Sheet15

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Sheet16

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*2 N2O5 (g) 4 NO2(g) + O2(g):Rate vs. TimeBecause reactant concentrationsdecrease, the rates of reactionsslow down over time.

Decomp of N2O5

Time (sec)Dt (sec)[N2O5] (M)-D[N2O5]Rate, -D[N2O5]/Dt[O2], MD[O2]Rate, D[O2]/Dt[NO2], MD[NO2]Rate, D[NO2]/DtLn[N2O5]0/[N2O5]1/[N2O5]-1/[N2O5]0

02.3300.0000.0000.000.00

11100111002.0800.2501.13E-050.1250.1251.13E-050.5000.5004.50E-050.110.05

1920081001.9100.1701.05E-050.2100.0851.05E-050.8400.3404.20E-050.200.09

31600124001.6700.2409.68E-060.3300.1209.68E-061.3200.4803.87E-050.330.17

52400208001.3500.3207.69E-060.4900.1607.69E-061.9600.6403.08E-050.550.31

72000196001.1100.2406.12E-060.6100.1206.12E-062.4400.4802.45E-050.740.47

112700407000.7200.3904.79E-060.8050.1954.79E-063.2200.7801.92E-051.170.96

138900262000.5500.1703.24E-060.8900.0853.24E-063.5600.3401.30E-051.441.39

188600497000.3400.2102.11E-060.9950.1052.11E-063.9800.4208.45E-061.922.51

Time (sec)Dt (sec)P(N2O5) (torr)-DP(N2O5)Rate, DP(N2O5)/DtP(O2)DP(O2)Rate, DP(O2)/DtP(NO2)DP(NO2)Rate, DP(NO2)/Dt

0348.400

6006002471018.45E-0251518.45E-02203202.8003.38E-01

1200600185625.17E-0282315.17E-02327124.0002.07E-01

1800600140453.75E-02104233.75E-0241790.0001.50E-01

2400600105352.92E-02122182.92E-0248770.0001.17E-01

300060078272.25E-02135142.25E-0254154.0009.00E-02

360060058201.67E-02145101.67E-0258140.0006.67E-02

420060044141.17E-0215271.17E-0260928.0004.67E-02

480060033119.17E-0315869.17E-0363122.0003.67E-02

54006002497.50E-0316257.50E-0364918.0003.00E-02

60006001865.00E-0316535.00E-0366112.0002.00E-02

720012001083.33E-0316943.33E-0367716.0001.33E-02

84001200552.08E-0317232.08E-0368710.0008.33E-03

96001200328.33E-0417318.33E-046914.0003.33E-03

[N2O5], M[NO2], M[O2] (M)Rate (M/sec)Rate/[N2O5] (1/sec)k (L-mol-1-sec-1)Temp(K)1/T (1/K)ln{k (L-mol-1-sec-1)}

2.212.001.001.14E-055.16E-064.8E-043183.14E-03-7.64

2.211.002.001.12E-055.07E-068.8E-043233.10E-03-7.04

2.210.000.001.13E-055.11E-061.6E-033283.05E-03-6.44

2.000.000.001.05E-055.25E-062.8E-033333.00E-03-5.88

1.790.000.009.67E-065.40E-06

1.510.000.007.83E-065.19E-06

1.230.000.006.31E-065.13E-06

0.920.000.004.81E-065.23E-06

&CKinetics - 8

Decomposition of N2O5 at 45C

2 N2O5 4 NO2 + O2

Decompostion of N2O5 at 45CDependence of Initial Rate on N2O5 Concentration

Rate Dependence on Temperature

Conc vs Time

2.3300

2.080.1250.5

1.910.210.84

1.670.331.32

1.350.491.96

1.110.612.44

0.720.8053.22

0.550.893.56

0.340.9953.98

&A

[N2O5] (M)

[O2], M

[NO2], M

Time, sec

Concentration, M


Rate vs Time Chart

0

0.0000112613

0.0000104938

0.0000096774

0.0000076923

0.0000061224

0.0000047912

0.0000032443

0.0000021127

&A

Rate, -D[N2O5]/Dt

Time, sec

Rate, D[]/Dsec

Decomposition of N2O5 at 45 C

Log Chart

0

0.1135003739

0.1987650255

0.3330446411

0.5457636751

0.7415082523

1.1743723345

1.4437052683

1.9246779289

&A

y= 10-5x

Ln[N2O5]0/[N2O5]

Time, sec

Ln[N2O5]0/[N2O5]


Inverse Chart

0

0.0515846814

0.0943756601

0.1696178459

0.3115561914

0.4717163515

0.9597043395

1.3889972688

2.5119919212

&A

1/[N2O5]-1/[N2O5]0

Time, sec

1/[N2O5] - 1/[N2O5]0


Activation Energy

-7.6417244541

-7.0355886505

-6.4377516497

-5.8781358618

&A

ln{k (L-mol-1-sec-1)}

1/T, (1/K)

ln k, L/molsec

Determining Activation Energy, ln k vs 1/T

Decomp of H2O2

Decomposition of H2O2(aq) at 40C

2 H2O2 2 H2O + O2

Time (sec)Dt (sec)[H2O2] (M)-D[H2O2] (M)Rate, -D[H2O2]/Dt (M/sec)Ln[H2O2]0/[H2O2]1/[H2O2]-1/[H2O2]0

01.0000.000.00

21600216000.5000.5000.00001157410.691.00

43200216000.2500.2500.0000057871.393.00

64800216000.1250.1250.00000289352.087.00

86400216000.0630.0630.00000144682.7715.00

k (sec-1)T (K)1/T, (1/K)Ln(k), (1/sec)

2.19E-115000.002000-24.545

6.92E+0110000.0010004.237

1.02E+0615000.00066713.835

1.23E+0820000.00050018.628

Conc vs Time, H2O2

1

0.5

0.25

0.125

0.0625

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Page &P

[H2O2] (M)

Time, sec

Concentration, M


Log & Inverse, H2O2

00

0.69314718061

1.38629436113

2.07944154177

2.772588722215

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Page &P

Ln[H2O2]0/[H2O2]

1/[H2O2]-1/[H2O2]0

Time, sec

Concentration Function


Act. En., H2O2

-24.5445344791

4.2370008626

13.8353131853

18.6276949133

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Page &P

Ln(k), (1/sec)

1/Temp, (1/K)

Ln k, (1/sec)

Activation Energy for Decomposition of Hydrogen Peroxide

Disprop. of BrO

Time (sec)Dt (sec)[BrO-1] (M)-D[BrO-1] (M)Rate, 1/3-D[BrO-1]/Dt (M/sec)-Ln[BrO-1]1/[BrO-1]

00.7500.28771.3333333333

10100.5280.2227.33E-030.63871.8939393939

20100.4080.1203.96E-030.89652.4509803922

30100.3320.0762.51E-031.10263.0120481928

40100.2800.0521.72E-031.27303.5714285714

50100.2420.0381.25E-031.41884.132231405

60100.2130.0299.57E-041.54654.6948356808

70100.1900.0237.59E-041.66075.2631578947

80100.1720.0185.94E-041.76035.8139534884

90100.1570.0154.95E-041.85156.3694267516

100100.1440.0134.29E-041.93796.9444444444

[BrO3-1], MD[BrO3-1]Rate, D[BrO3-1]/Dt (M/sec)

0.0000

0.07330.07337.33E-03

0.11290.03963.96E-03

0.13790.02512.51E-03

0.15510.01721.72E-03

0.16760.01251.25E-03

0.17720.00969.57E-04

0.18480.00767.59E-04

0.19070.00595.94E-04

0.19570.00494.95E-04

0.20000.00434.29E-04

[Br-1], MD[Br-1]Rate, 1/2 D[Br-1]/Dt (M/sec)

0.0000

0.14870.14877.44E-03

0.22910.08044.02E-03

0.28010.05092.55E-03

0.31490.03481.74E-03

0.34040.02551.27E-03

0.35980.01949.72E-04

0.37520.01547.70E-04

0.38730.01216.03E-04

0.39730.01005.02E-04

0.40600.00874.36E-04

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Page &P

Disproportionation of Hypobromite Ion3 BrO-1 BrO3-1 + 2 Br-1

Conc vs Time, BrO

0.75

0.528

0.408

0.332

0.28

0.242

0.213

0.19

0.172

0.157

0.144

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Page &P

[BrO-1] (M)

Time, sec

Concentration of BrO-1, M


Log & Inverse, BrO

0.28768207251.3333333333

0.63865899531.8939393939

0.89648810462.4509803922

1.10262031013.0120481928

1.27296567583.5714285714

1.41881755284.132231405

1.54646311334.6948356808

1.66073120685.2631578947

1.76026080225.8139534884

1.85150947366.3694267516

1.93794197946.9444444444

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Page &P

-Ln[BrO-1]

1/[BrO-1]

Time, sec

Concentraiton Function


HCN + H2O

Time (sec)Dt (sec)[HCN] (M)-D[HCN] (M)Rate, -D[HCN]/Dt (M/sec)[NH4HCO2], MD[NH4HCO2]Rate, D[NH4HCO2]/Dt (M/sec)

00.10000.0000

2.00E+052.00E+050.09840.00168.00E-090.00160.00168.00E-09

5.00E+053.00E+050.09610.00237.67E-090.00390.00237.67E-09

1.00E+065.00E+050.09230.00387.60E-090.00770.00387.60E-09

2.00E+061.00E+060.08510.00727.20E-090.01490.00727.20E-09

3.00E+061.00E+060.07850.00666.60E-090.02150.00666.60E-09

4.00E+061.00E+060.07240.00616.10E-090.02760.00616.10E-09

5.00E+061.00E+060.06680.00565.60E-090.03320.00565.60E-09

6.00E+061.00E+060.06170.00515.10E-090.03830.00515.10E-09

7.00E+061.00E+060.05690.00484.80E-090.04310.00484.80E-09

8.00E+061.00E+060.05250.00444.40E-090.04750.00444.40E-09

9.00E+061.00E+060.04840.00414.10E-090.05160.00414.10E-09

1.00E+071.00E+060.04470.00373.70E-090.05530.00373.70E-09

2.00E+071.00E+070.01990.02482.48E-090.08010.02482.48E-09

3.00E+071.00E+070.00890.01101.10E-090.09110.01101.10E-09

4.00E+071.00E+070.00400.00494.90E-100.09600.00494.90E-10

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HCN(aq) + H2O(l) NH4HCO2(aq)

HCN + H2O

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

00

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[HCN] (M)

[NH4HCO2], M

Time (sec)

Concentration, M

HCN + H2O NH4HCO2

CH3Cl + H2O

Time (sec)Dt (sec)[CH3Cl] (M)-D[CH3Cl] (M)Rate, -D[CH3Cl]/Dt (M/sec)[CH3OH], MD[CH3OH]Rate, D[CH3OH]/Dt (M/sec)[HCl], MD[HCl]Rate, D[HCl]/Dt (M/sec)

00.10000.00000.0000

40400.08230.01771.46E-040.01770.01774.43E-040.01770.01774.43E-04

80400.06780.01451.20E-040.03220.01453.63E-040.03220.01453.63E-04

120400.05580.01209.90E-050.04420.01203.00E-040.04420.01203.00E-04

160400.04600.00988.09E-050.05400.00982.45E-040.05400.00982.45E-04

200400.03780.00826.77E-050.06220.00822.05E-040.06220.00822.05E-04

240400.03110.00675.53E-050.06890.00671.68E-040.06890.00671.68E-04

280400.02560.00554.54E-050.07440.00551.38E-040.07440.00551.38E-04

320400.02110.00453.71E-050.07890.00451.13E-040.07890.00451.13E-04

360400.01740.00373.05E-050.08260.00379.25E-050.08260.00379.25E-05

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Hydrolysis of CH3Cl@ 90CCH3Cl + H2O CH3OH + HCl

CO + NO2

Time (sec)Dt (sec)[CO], (M)-D[CO], (M)[NO2], (M)-D[NO2], (M)Rate, -D[CO]/Dt, (M/sec)

00.1000.100

10100.0670.0330.0670.0333.30E-03

20100.0500.0170.0500.0171.70E-03

30100.0400.0100.0400.0101.00E-03

40100.0330.0070.0330.0077.00E-04

100600.0170.0160.0170.0162.67E-04

10009000.0020.0150.0020.0151.67E-05

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Page &P

Oxidation of CO by NO2

CO(g) + NO2(g) CO2(g) + NO(g)

CH3OH + HCl

Time (sec)Dt (sec)pH[H+1], (M)[HCl], M-D[HCl]Rate, D[HCl]/Dt (M/sec)Ln[HCl]0/[HCl]1/[HCl] - 1/[HCl]0Time (sec)Dt (sec)[SO2Cl2], (M)-D[SO2Cl2], (M)Rate, -D[SO2Cl2]/Dt, (M/sec)ln[SO2Cl2]0/[SO2Cl2]1/[SO2Cl2]

0-0.271.861.860.0000.00001.00E-020.0000

8080-0.221.661.660.202.53E-030.1150.06620209.70E-033.00E-041.50E-050.0303

15979-0.181.511.510.151.85E-030.2070.12450309.28E-034.20E-041.40E-050.0758

314155-0.121.321.320.201.26E-030.3450.222100508.61E-036.70E-041.34E-050.15016

628314-0.01001.021.020.299.39E-040.5990.4402001007.41E-031.20E-031.20E-050.30035

4002005.49E-031.92E-039.60E-060.60082

7003003.50E-031.99E-036.63E-061.050186

10003002.30E-031.20E-034.00E-061.470335

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Page &P

Nucleophilic Substitution

CH3OH(aq) + HCl(aq) CH3Cl(aq) + H2O(l)

Decomposition of SO2Cl2@ 320CSO2Cl2 SO2 + Cl2

CH3OH + HCl

0

0

0

0

0

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[HCl], M

Time (sec)

[HCl], M

Nucleophilic Substitution CH3OH(aq) + HCl(aq) CH3Cl(aq) + H2O(l)

Sheet8

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[SO2Cl2], (M)

Time (sec)

[SO2Cl2], M

Decomposition of SO2Cl2 @ 325CSO2Cl2 SO2 + Cl2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

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Page &P

1/[SO2Cl2]

Time (sec)

1/[SO2Cl2] - 1/[SO2Cl2]0

Decompostion of SO2Cl2, 1/[SO2Cl2] vs Time

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

&A

Page &P

ln[SO2Cl2]0/[SO2Cl2]

Time (sec)

Ln[SO2Cl2]0/[SO2Cl2]

Decompositon of SO2Cl2, Ln[SO2Cl2] vs Time

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

&A

Page &P

Ln[HCl]0/[HCl]

Time (sec)

Ln[HCl]0/[HCl]

Nucleophilic Substitution, CH3OH + HCl, Ln[HCl] vs Time

0

0

0

0

0

0

0

0

0

0

&A

Page &P

1/[HCl] - 1/[HCl]0

Time (sec)

1/[HCl] - 1/[HCl]0

Nucleophilic Substitution, CH3OH + HCl, 1/[HCl] vs time

0

0

0

0

0

0

0

0

0

0

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Sheet9

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Sheet10

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Page &P

Sheet11

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Sheet12

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Page &P

Sheet13

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Page &P

Sheet14

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Page &P

Sheet15

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Sheet16

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Page &P

*Collision TheoryIn order for a reaction to take place, the reacting molecules must collide with each other.Once molecules collide they may react together or they may not, depending on two factors:

Whether the collision has enough energy to start to break the bonds holding reactant molecules together."Whether the reacting molecules collide in the proper orientation for new bonds to form.

*Effective CollisionsCollisions in which these two conditions are met (and therefore the reaction occurs) are called effective collisions. The higher the frequency of effective collisions, the faster the reaction rate.There is a minimum energy needed for a collision to be effective. We call this the activation energy.

The lower the activation energy, the faster the reaction will be.

*Effective Collisions:Kinetic Energy FactorFor a collision to lead to overcoming the energy barrier, the reacting molecules must have sufficient kinetic energy so that when they collide, it can form the activated complex().

*

*Effective Collisions:Orientation Effect()

*

*Reaction Energy Diagram

*

*The higher the concentration of reactant molecules, this increases the frequency of reactant molecule collisions the faster the reaction will generally go.Since reactants are consumed as the reaction proceeds, the speed of a reaction generally slows over time.

Factors Effecting Reaction Rate:Reactant Concentration

*Effect of Concentration on RateLow concentrations of reactant molecules lead to fewer effective collisions, therefore a slower reaction rate.High concentrations of reactant molecules lead to more effective collisions, therefore a faster reaction rate.

*Increasing the temperature increases the energy so that their collisions can overcome the activation energy.And, increasing the temperature also increases the frequency of collisions. Both these mean that increasing temperature increases the reaction rate.

Factors Effecting Reaction Rate:Temperature

Effect of Temperature on RateLow temperatures lead to fewer molecules with enough energy to overcome the activation energy, and less frequent reactant collisions, therefore a slower reaction rateHigh temperatures lead to more molecules with enough energy to overcome the activation energy, and more frequent reactant collisions, therefore, a faster reaction rate.

*Activation EnergyThe energy barrier() that prevents any collision between molecules from being an effective collision is called the activation energy.The larger the activation energy of a reaction, the slower it will be.

At a given temperature.

*Exothermic Reaction

Progress of reactionRelative potential energyReactantsProducts

Activationenergy,smallDHreactionActivationenergy,large

*Endothermic ReactionProgress of reactionRelative potential energyReactantsProducts

ActivationenergyDHreaction

*Effect of Catalysts on RateA catalyst() is a substance that increases the rate of a reaction, but is not consumed in the reaction.Catalysts lower the activation energy of a reaction.Catalysts work by providing an easier pathway for the reaction.

*Catalyst Effect on Activation Energy

*EnzymesEnzymes() are protein molecules produced by living organisms that catalyze() chemical reactions.The enzyme molecules have an active site() to which organic molecules bind.When the organic molecule is bound to the active site, certain bonds are weakened().This allows a particular chemical change to occur with greater ease and speed.

i.e., the activation energy is lowered.

*Reaction DynamicsIf the products of a reaction are removed from the system as they are made, then a chemical reaction will proceed until the limiting reactants are used up.However, if the products are allowed to accumulate; they will start reacting together to form the original reactants. This is called the reverse reaction.Reactions that can proceed in both the forward and reverse directions are called reversible reactions.

*

*Reaction DynamicsThe forward reaction slows down as the amounts of reactants decreases. At the same time, the reverse reaction speeds up as the concentration of the products increases. Eventually, the forward reaction is using reactants and making products as fast as the reverse reaction is using products and making reactants. This is called chemical equilibrium.

Dynamic equilibrium is reached when the rates of two opposite processes are the same.

*

*Chemical EquilibriumWhen a reaction reaches equilibrium, the amounts of reactants and products in the system stay constant.The forward and reverse reactions still continue.Because they go at the same rate, the amounts of materials do not change.

*

EquilibriumInitially, we only have reactant molecules in the mixture. The reaction can only proceed in the forward direction, making products.As the reaction proceeds, the forward reaction slows down as the reactants get used up. At the same time, the reverse reaction speeds up as product concentration increases.Eventually, the forward and reverse rates are equal. At this time equilibrium is established.Once equilibrium is established, the concentrations of the reactants and products in the final mixture do not change, (unless conditions are changed).

*EquilibriumTimeRateInitially, only the forwardreaction takes place.As the forward reaction proceedsit makes products and uses reactants.Because the reactant concentration decreases, the forward reaction slows.As the products accumulate, thereverse reaction speeds up.Eventually, the reaction proceedsin the reverse direction as fast asit proceeds in the forward direction.At this time equilibrium is established.Once equilibrium is established,the forward and reverse reactions proceed at the same rate, so theconcentrations of all materialsstay constant.

*Hypothetical Reaction2 Red BlueThe reaction slows over time,but the red molecules never run out!At some time between 100 and 110 sec,the concentrations of both the red andthe blue molecules no longer changeequilibrium has been established.Notice that equilibrium does not meanthat the concentrations are equal!Once equilibrium is established, the rateof red molecules turning into blue is thesame as the rate of blue molecules turning into red.

Time[Red][Blue]00.4000.000100.2080.096200.1900.105300.1800.110400.1740.113500.1700.115600.1680.116700.1670.117800.1660.117900.1650.1181000.1650.1181100.1640.1181200.1640.1181300.1640.1181400.1640.1181500.1640.118

*

*Hypothetical Reaction2 Red Blue, Continued

Sheet1

Choose the reaction you wish to investigate

Choose the Initial Concentration of Chemicals[A]init =[Y]init =

00

Choose the Celsius temperature you wish to useChoose the time interval between readings

Choose the value of DG, in Joules

Choose the order for each reactant in the forward rate equationOrder of A =0

Choose the order for each product in the reverse rate equationOrder of Y =0

Choose the activation energy, in joules, for the forward reaction

Given the above information, the equilibrium constant, K, for the reaction will equal3.2

Given the above information, the value of the forward reaction rate constant, kf, will equal0.15

Given the above information, the value of the reverse reaction rate constant, kr, will equal0.0475

Data Sheet

Reaction ListCoeff ACoeff BCoeff YCoeff ZCoeffA =2Init Conc[A]init =0.4OrdersA order =2

2 A ----> YA ----> Y1010CoeffB =00.1[B]init =0.10B order =1

2 A ----> Y2010CoeffY =10.2[Y]init =01Y order =1

A ----> 2 Y1020CoeffZ =00.3[Z]init =0.42Z order =0

3 A ----> Y30100.4

A ----> 3 Y10300.5

2 A ----> 3 Y20300.6

3 A ----> 2 Y30200.7

A + B ----> Y11100.8

2 A + B ----> Y21100.9

A + B ----> 2 Y11201

A + B ----> Y + Z1111

2 A + B ----> Y + Z2111

A + B ----> 2 Y + Z1121

Time IntervalTime Interval List, secondsTotal Time

20.550

1100

2200

5500

101000

Temp, CTemp List, CTemp, K

250-100523

0

50R, J/mol-K

1008.314

500

DGDG List, JKx

-5000-250003.2E+000

-20000Kcalc

-150003.1578622343

-10000

-5000

0

5000

10000

15000

20000

25000

Ea forwardEa List, jouleskfkf_calcForward Collision Freq, Afkf/kr

700010001.50E-010.14993768880.753.1578947368

3000

Ea reverse5000krkr_calcReverse Collision Freq, Ar

1200070004.75E-020.04748075680.75

10000

Calc Sheet

Mole MultiplierAvog. Number

1.66E-196.02E+23

Time[Red]0[Blue]0Molecules AMolecules BMolecules YMolecules ZRate ForwardRate ReverseMolecules A ReactMolecules B ReactMolecules Y ReactMolecules Z ReactMolecules A MadeMolecules B MadeMolecules Y MadeMolecules Z Made

00.4000400000000.024038400000019200

20.361725880600.01920668390361600192000.01962684190.000912317528390408014200

40.333406025300.03337161330333290333600.01667393670.00158515162223011022011120

60.311388363200.04438544610311280443700.01454440690.0021083087181101903809060

80.29365219100.0532585340293550532400.01293474140.0025297804151902705407600

100.27899709100.06059108570278900605700.01167590650.0028780766130303507006520

120.266662798700.06676323360266570667400.01066635720.0031712536113704208405690

140.256129132900.07203506820256040720100.00984031990.0034216657100804909805040

160.24702596500.07658665220246940765600.00915327410.003637866904056011204520

180.239103207900.08054803070239020805200.00857555160.0038260315820062012404100

200.23214078500.08402924220232060840000.00808340160.003991389750067013403750

220.225978640600.08711031440225900870800.00765995190.0041377399692072014403460

240.220496732900.08985126820220420898200.00729282140.0042679352643077015403220

260.215605030600.09230212110215530922700.00697282940.0043843508601081016203010

280.211213502300.0945028870211140944700.00669167150.0044888871565085017002830

300.207262127200.09648357630207190964500.00644363840.0045829699534088017602670

320.203680880900.09827419940203610982400.00622288520.0046680245507092018402540

340.200449756500.09989476340200380998600.00602701570.0047450013483095019002420

360.197518736500.101365275101974501013300.00585204770.0048148506462098019602310

380.194857810500.102695738101947901026600.00569543490.00487804764440100020002220

400.192416961100.103916162801923501038800.0055536430.00493601774270103020602140

420.190206191800.105026549201901401049900.00542675930.00498876114130105021002070

440.188175485100.106046904301881101060100.0053115020.0050372284000107021402000

460.186314837600.106977228101862501069400.00520698280.00508141833880109021801940

480.184614245800.10782752401845501077900.0051123630.00512180743770110022001890

500.183043699200.10861779901829801085800.00502574940.00515934553680112022401840

520.181603197900.109338049601815401093000.00494695820.00519355743590114022801800

540.180292741900.109998279401802301099600.00487582090.00522491833520115023001760

560.179072317200.110608491801790101105700.00481003420.00525390343440116023201720

580.177951927300.111168686701778901111300.00475003330.00528051263380117023401690

600.176911565200.111688867701768501116500.00469465530.00530522123320118023601660

620.17595123100.112169034801758901121300.00464382540.00532802923270119023801640

640.175060921200.112619191501750001125800.00459694890.00534941163220120024001610

660.174240635700.113029334201741801129900.00455396990.00536889343170121024201590

680.173490374700.113409466501734301133700.00451483650.00538694973130122024401570

700.172800134400.113759588301727401137200.0044789830.00540358043090123024601550

720.172169915100.114079699701721101140400.0044463720.00541878573060124024801530

740.171589713200.114369800701715301143300.00441645450.00543256553030124024801520

760.171039521800.114649898201709801146100.00438817770.00544587023000125025001500

780.170539347700.114899985201704801148600.00436255040.00545774932970125025001490

800.170069184100.115140068701700101151000.00433852910.00546915332950126025201480

820.169639034400.115360145301695801153200.00431661030.00547960692930126025201470

840.169228891700.115570218401691701155300.00429576270.00548958542910127025401460

860.168858762800.115760284601688001157200.00427699230.00549861352890127025401450

880.16850864100.115940347201684501159000.00425927430.00550716652870128025601440

900.168198533100.116100402901681401160600.0042436120.00551476912850128025601430

920.167908432100.116250455201678501162100.00422898620.00552189662840128025601420

940.167628334700.116390503901675701163500.00421488880.00552854892830129025801420

960.167378247600.116520549201673201164800.00420232170.00553472612810129025801410

980.167148167600.116640590901670901166000.00419077650.00554042812800129025801400

1000.16692809100.116750629201668701167100.00417974810.00554565492790129025801400

1020.166718017900.116860667501666601168200.00416923460.00555088172780130026001390

1040.166537955200.116950698801664801169100.00416023360.00555515822770130026001390

1060.16636789600.117040730201663101170000.00415174150.00555943472760130026001380

1080.166207840300.11712075801661501170800.00414375690.0055632362750130026001380

1100.166057788100.117200785901660001171600.00413627830.00556703732750130026001380

1120.165907735900.117280813701658501172400.00412880650.00557083872740131026201370

1140.165787694100.117340834601657301173000.00412283390.00557368962730131026201370

1160.165677655800.117400855501656201173600.00411736280.00557654062730131026201370

1180.165567617500.117460876401655101174200.00411189540.00557939162720131026201360

1200.165467582700.117510893801654101174700.00410692810.00558176752720131026201360

1220.165367547900.117560911201653101175200.00410196390.00558414332710131026201360

1240.165277516600.117610928601652201175700.00409749860.00558651912710131026201360

1260.165187485200.11766094601651301176200.00409303580.00558889492700131026201350

1280.165107457400.117700959901650501176600.00408907090.00559079562700132026401350

1300.165047436500.117730970401649901176900.00408609840.00559222112700132026401350

1320.164987415600.117760980801649301177200.00408312710.00559364662690132026401350

1340.164937398200.117790991301648801177500.00408065180.00559507212690132026401350

1360.164887380800.117821001701648301177800.00407817730.00559649762690132026401350

1380.164837363400.117851012201647801178100.00407570350.00559792312690132026401350

1400.16478734600.117881022601647301178400.00407323040.00559934862680132026401340

1420.164747332100.117901029601646901178600.00407125250.00560029892680132026401340

1440.164707318100.117921036501646501178800.00406927510.00560124922680132026401340

1460.164667304200.117941043501646101179000.00406729820.00560219962680132026401340

1480.164627290300.117961050401645701179200.00406532170.00560314992680132026401340

1500.164587276400.117981057401645301179400.00406334570.00560410022670132026401340

1520.164557265900.118001064401645001179600.00406186410.00560505062670132026401340

1540.164527255500.118021071301644701179800.00406038270.00560600092670132026401340

1560.16449724500.118041078301644401180000.00405890150.00560695122670132026401340

1580.164467234600.118061085301644101180200.00405742070.00560790152670132026401340

1600.164437224200.118081092201643801180400.00405594010.00560885192670132026401340

1620.164407213700.118101099201643501180600.00405445980.00560980222670132026401340

1640.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1660.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1680.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1700.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1720.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1740.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1760.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1780.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1800.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1820.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1840.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1860.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1880.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1900.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1920.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1940.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1960.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

1980.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2000.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2020.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2040.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2060.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2080.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2100.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2120.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2140.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2160.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2180.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2200.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2220.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2240.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2260.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2280.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2300.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2320.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2340.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2360.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2380.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2400.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2420.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2440.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2460.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2480.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2500.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2520.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2540.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2560.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2580.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2600.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2620.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2640.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2660.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2680.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2700.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2720.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2740.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2760.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2780.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2800.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2820.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2840.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2860.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2880.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2900.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2920.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2940.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2960.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

2980.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3000.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3020.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3040.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3060.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3080.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3100.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3120.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3140.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3160.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3180.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3200.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3220.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3240.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3260.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3280.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3300.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3320.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3340.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3360.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3380.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3400.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3420.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3440.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3460.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3480.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3500.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3520.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3540.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3560.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3580.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3600.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3620.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3640.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3660.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3680.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3700.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3720.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3740.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3760.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3780.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3800.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3820.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3840.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3860.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3880.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3900.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3920.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3940.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3960.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

3980.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

4000.164377203300.118121106101643201180800.00405297970.00561075252660133026601330

Conc vs Time

0.40

0.36172588060.0192066839

0.33340602530.0333716133

0.31138836320.0443854461

0.2936521910.053258534

0.2789970910.0605910857

0.26666279870.0667632336

0.25612913290.0720350682

0.2470259650.0765866522

0.23910320790.0805480307

0.2321407850.0840292422

0.22597864060.0871103144

0.22049673290.0898512682

0.21560503060.0923021211

0.21121350230.094502887

0.20726212720.0964835763

0.20368088090.0982741994

0.20044975650.0998947634

0.19751873650.1013652751

0.19485781050.1026957381

0.19241696110.1039161628

0.19020619180.1050265492

0.18817548510.1060469043

0.18631483760.1069772281

0.18461424580.107827524

0.18304369920.108617799

0.18160319790.1093380496

0.18029274190.1099982794

0.17907231720.1106084918

0.17795192730.1111686867

0.17691156520.1116888677

0.1759512310.1121690348

0.17506092120.1126191915

0.17424063570.1130293342

0.17349037470.1134094665

0.17280013440.1137595883

0.17216991510.1140796997

0.17158971320.1143698007

0.17103952180.1146498982

0.17053934770.1148999852

0.17006918410.1151400687

0.16963903440.1153601453

0.16922889170.1155702184

0.16885876280.1157602846

0.1685086410.1159403472

0.16819853310.1161004029

0.16790843210.1162504552

0.16762833470.1163905039

0.16737824760.1165205492

0.16714816760.1166405909

0.1669280910.1167506292

0.16671801790.1168606675

0.16653795520.1169506988

0.1663678960.1170407302

0.16620784030.117120758

0.16605778810.1172007859

0.16590773590.1172808137

0.16578769410.1173408346

0.16567765580.1174008555

0.16556761750.1174608764

0.16546758270.1175108938

0.16536754790.1175609112

0.16527751660.1176109286

0.16518748520.117660946

0.16510745740.1177009599

0.16504743650.1177309704

0.16498741560.1177609808

0.16493739820.1177909913

0.16488738080.1178210017

0.16483736340.1178510122

0.1647873460.1178810226

0.16474733210.1179010296

0.16470731810.1179210365

0.16466730420.1179410435

0.16462729030.1179610504

0.16458727640.1179810574

0.16455726590.1180010644

0.16452725550.1180210713

0.1644972450.1180410783

0.16446723460.1180610853

0.16443722420.1180810922

0.16440721370.1181010992

0.16437720330.1181211061

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[Red]

[Blue]

Time, sec

Concentration

Concentration vs. Time for 2 Red Blue

0

0

1

1

0.4

0.4

5

5

-5000

-5000

2 A ----> Y

2 A ----> Y

7000

7000

2

2

0

0

0.1

0.1

0.4

0.4

1

1

2

2

250

250

MBD000000FC.unknown

MBD0000023C.unknown

MBD0000037C.unknown

MBD00198947.unknown

MBD0057AC9A.unknown

MBD005704B5.unknown

MBD000003CC.unknown

MBD000003D0.unknown

MBD00000380.unknown

MBD000002DC.unknown

MBD0000032C.unknown

MBD00000330.unknown

MBD000002E0.unknown

MBD0000028C.unknown

MBD00000290.unknown

MBD00000240.unknown

MBD0000019C.unknown

MBD000001EC.unknown

MBD000001F0.unknown

MBD000001A0.unknown

MBD0000014C.unknown

MBD00000150.unknown

MBD00000100.unknown

MBD00000050.unknown

MBD000000A4.unknown

*

*Equilibrium EqualThe rates of the forward and reverse reactions are equal at equilibrium.But that does not mean the concentrations of reactants and products are equal.Some reactions reach equilibrium only after almost all the reactant molecules are consumedwe say the position of equilibrium favors the products.Other reactions reach equilibrium when only a small percentage of the reactant molecules are consumedwe say the position of equilibrium favors the reactants.

*An Analogy: Population ChangesWhen Narnians feel overcrowded, some will emigrate to Middle Earth.However, as time passes, emigration will occur in both directions at the same rate, leading to populations in Narnia and Middle Earth that are constant, though not necessarily equal.

*Equilibrium ConstantEven though the concentrations of reactants and products are not equal at equilibrium, there is a relationship between them.For the reaction H2(g) + I2(g) 2HI(g) at equilibrium, the ratio of the concentrations raised to the power of their coefficients is constant.

*Equilibrium ConstantFor the general equation aA + bB cC + dD, the relationship is given below:

The lowercase letters represent the coefficients of the balanced chemical equation.Always products over reactants.The constant is called the equilibrium constant, Keq.

*Writing Equilibrium Constant ExpressionsFor aA + bB cC + dD, the equilibrium constant expression is:

*Equilibrium Constants for Heterogeneous() EquilibriaPure substances in the solid and liquid state have constant concentrations.

Adding or removing some does not change the concentration because they do not expand to fill the container or spread throughout a solution.Therefore, these substances are not included in the equilibrium constant expression.

*Write the Equilibrium Constant Expressions, Keq, for Each of the Following:2 CO2(g) 2 CO(g) + O2(g) BaSO4(s) Ba+2(aq) + SO4-2(aq)CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)

*Write the Equilibrium Constant Expressions, Keq, for Each of the Following, Continued:2 CO2(g) 2 CO(g) + O2(g) BaSO4(s) Ba+2(aq) + SO4-2(aq)CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)

*What Does the Value of Keq Imply? When the value of Keq > > 1, we know that when the reaction reaches equilibrium, there will be many more product molecules present than reactant molecules.

The position of equilibrium favors products.When the value of Keq < < 1, we know that when the reaction reaches equilibrium, there will be many more reactant molecules present than product molecules.

The position of equilibrium favors reactants.

*A Large Equilibrium Constant

*A Small Equilibrium Constant

*Write the Equilibrium Constant Expressions, Keq, and Predict the Position of Equilibrium for Each of the Following:2 HF(g) H2(g) + F2(g) Keq = 1 10-952 SO2(g) + O2(g) 2 SO3(g) Keq = 8 1025N2(g) + 2 O2(g) 2 NO2(g) Keq = 3 10-17

Write the Equilibrium Constant Expressions, Keq, and Predict the Position of Equilibrium for Each of the Following:2 HF(g) H2(g) + F2(g) Keq = 1 10-952 SO2(g) + O2(g) 2 SO3(g) Keq = 8 1025N2(g) + 2 O2(g) 2 NO2(g) Keq = 3 10-17

Favors reactants.Favors products.Favors reactants.

*Calculating KeqThe value of the equilibrium constant may be determined by measuring the concentrations of all the reactants and products in the mixture after the reaction reaches equilibrium, then substituting() in the expression for Keq.Although you may have different amounts of reactants and products in the equilibrium mixture, the value of Keq will always be the same.

The value of Keq depends only on the temperature. The value of Keq does not depend on the amounts of reactants or products with which you start.

*Initial and Equilibrium Concentrations forH2(g) + I2(g) 2HI(g)

InitialEquilibriumEquilibriumConstant[H2][I2][HI][H2][I2][HI]0.500.500.00.110.110.780.00.00.500.0550.0550.390.500.500.500.1650.1651.171.00.50.00.530.0330.934

*Example 3.3Find the Value of Keq for the Reaction from the Given Concentrations:2 CH4(g) C2H2(g) + 3 H2(g).Keq is unitless.Check:Solve:

Solution Map:

Relationships:[CH4] = 0.0203 M, [C2H2] = 0.0451 M, [H2] = 0.112 M KeqGiven:Find:

*

*PracticeCalculate Keq for the Reaction 2 NO2(g) N2O4(g)at 100 C if the Equilibrium Concentrations Are [NO2] = 0.0172 M and [N2O4] = 0.0014 M.

PracticeFind the Value of Keq for the Reaction from the Given Concentrations: 2 NO2(g) N2O4(g).Keq is unitless.Check:Solve:

Solution Map:

Relationships:[NO2] = 0.0172 M, [N2O4] = 0.0014 M KeqGiven:Find:

*

*Example 3.4Find the Value of [HI] for the Reaction at Equilibrium from the Given Concentrations and Keq: H2(g) + I2(g) 2HI(g)Solve:

Solution Map:

Relationships:[I2] = 0.020 M, [H2] = 0.020 M, Keq = 69 [HI]Given:Find:

*

*Disturbing and Re-EstablishingEquilibrium Once a reaction is at equilibrium, the concentrations of all the reactants and products remain the same.However, if the conditions are changed, the concentrations of all the chemicals will change until equilibrium is re-established.The new concentrations will be different, but the equilibrium constant will be the same.

Unless you change the temperature.

Additional aspects of Free EnergyEven though a reaction has a negative G it may occur too slowly to be observed (i.e. combustion).Thermodynamics gives us the direction of a spontaneous process, it does not give us the rate of the process.A nonspontaneous process can be driven if coupled with a spontaneous process this is very important in life processes (i.e., respiration to form ATP), and can be used in industrial processes, such as smelting. To calculate K values, use G = -RT ln Keq.

This refers to the G difference of the standard states of compounds, before equilibrium is attained.

Calculating Keq from G valuesR = 8.314 J/mol-KLets calculate Keq from the following reaction, which we previously studied in the Equilibrium chapter: N2O4(g) 2NO2(g)Gf 98.3 2(51.8) G = 5.3 kJG = -RT ln K5300 = -8.314(407) ln Kln K = -1.57 K = 0.208 -- very close to the experimental value

Lets take a look at the dissolution of NH4Cl. NH4Cl(s) NH4+(aq) + Cl-(aq)Hf -314.4 -132.5 -167.2 H = +14.7S 0.0946 0.1135 0.0565 S = +0.0754G = H T S = 14.7 (298)(0.0754) = 14.7 22.47 = -7.77 kJThe reaction is endothermic, but is spontaneous!Hence, ammonium chloride is excellent for cold packs.

*Le Chteliers PrincipleLe Chteliers principle guides us in predicting the effect on the position of equilibrium when conditions change.When a chemical system at equilibrium is disturbed, the system shifts in a direction that will minimize the disturbance.

*The Effect of Concentration Changes on EquilibriumAdding a reactant will decrease the amounts of the other reactants and increase the amount of the products until a new position of equilibrium is found.

That has the same Keq.Removing a product will increase the amounts of the other products and decrease the amounts of the reactants.

You can use to this to drive a reaction to completion! Remember: Adding more of a solid or liquid does not change its concentration and, therefore, has no effect on the equilibrium.

*The Effect of Concentration Changes on EquilibriumWhen NO2is added,some of itcombinesto make more N2O4.

*The Effect of Concentration Changes on EquilibriumWhen N2O4is added,some of itdecomposesto make more NO2.

*PracticePredict the Effect on the Equilibrium When the Underlined Substance Is Added to the Following Systems:2 CO2(g) 2 CO(g) + O2(g) BaSO4(s) Ba2+(aq) + SO42-(aq)CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)

*PracticePredict the Effect on the Equilibrium When the Underlined Substance Is Added to the Following Systems, Continued:2 CO2(g) 2 CO(g) + O2(g) BaSO4(s) Ba2+(aq) + SO42-(aq)CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)

Shift right, removing some of the added CO2 andincreasing the concentrations of CO and O2.Shift left, removing some of the added Ba2+ and reducing the concentration of SO42-.Shift right, removing some of the added CO2 and decreasing the O2, while increasing the concentration of CO2.

*Effect of Volume Changeon EquilibriumFor solids, liquids, or solutions, changing the size of the container has no effect on the concentration.Changing the volume of a container changes the concentration of a gas.

Same number of moles, but different number of liters, resulting in a different molarity.

*Effect of Volume Changeon EquilibriumDecreasing the size of the container increases the concentration of all the gases in the container.

This increases their partial pressures.If their partial pressures increase, then the total pressure in the container will increase.According to Le Chteliers principle, the equilibrium should shift to remove that pressure.The way to reduce the pressure is to reduce the number of molecules in the container.When the volume decreases, the equilibrium shifts to the side with fewer molecules.

*The Effect of Volume Change on Equilibrium

*PracticePredict the Effect on the Equilibrium When the Volume Is Reduced.2 CO2(g) 2 CO(g) + O2(g) BaSO4(s) Ba2+(aq) + SO42-(aq)CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)

*PracticePredict the Effect on the Equilibrium When the Volume Is Reduced2 CO2(g) 2 CO(g) + O2(g) BaSO4(s) Ba2+(aq) + SO42-(aq)CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)

Shift left because there are fewer gas moleculeson the reactant side than on the product side.No effect because none of the substances are gases.Shift right because there are fewer gas moleculeson the product side than on the reactant side.

*The Effect of Temperature Changes on EquilibriumExothermic reactions release energy and endothermic reactions absorb energy.If we write heat as a product in an exothermic reaction or as a reactant in an endothermic reaction, it will help us use Le Chteliers principle to predict the effect of temperature changes.

However, heat is not matter and not written in a proper equation.

*The Effect of Temperature Changes on Equilibrium for Exothermic ReactionsFor an exothermic reaction, heat is a product.Increasing the temperature is like adding heat.According to Le Chteliers principle, the equilibrium will shift away from the added heat.The concentrations of C and D will decrease and the concentrations of A and B will increase.The value of Keq will decrease.How will decreasing the temperature effect the system?

aA + bB cC + dD + heat

*The Effect of Temperature Changes on Equilibrium for Endothermic ReactionsFor an endothermic reaction, heat is a reactant.Increasing the temperature is like adding heat.According to Le Chteliers principle, the equilibrium will shift away from the added heat.The concentrations of C and D will increase and the concentrations of A and B will decrease.The value of Keq will increase.How will decreasing the temperature effect the system?

Heat + aA + bB cC + dD

*The Effect of Temperature Changes on Equilibrium

*PracticePredict the Effect on the Equilibrium When the Temperature Is Reduced.Heat + 2 CO2(g) 2 CO(g) + O2(g) BaSO4(s) Ba2+(aq) + SO42-(aq)(endothermic)CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l)(exothermic)

*PracticePredict the Effect on the Equilibrium When the Temperature Is ReducedHeat + 2 CO2(g) 2 CO(g) + O2(g) Heat + BaSO4(s) Ba2+(aq) + SO42-(aq)CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l) + Heat

Shift left, reducing the value of Keq.Shift left, reducing the value of Keq.Shift right, increasing the value of Keq.

*Solubility and Solubility ProductEven insoluble salts dissolve somewhat in water.

Insoluble = less than 0.1 g per 100 g H2O.The solubility of insoluble salts is described in terms of equilibrium between undissolved solid and aqueous ions produced.

AnYm(s) n A+(aq) + m Y-(aq)Equilibrium constant for this process is called the solubility product constant, Ksp.

Ksp = [A+]n[Y-]mIf there is undissolved solid in equilibrium with the solution, the solution is saturated.Larger Ksp = more soluble.

For salts that produce the same number of ions.

*ExampleDetermine the Ksp of PbBr2 if its Solubility Is 1.44 x 10-2 M.PbBr2(s) Pb2+(aq) + 2 Br(aq)init -- 0 0equil -- 0.0144 0.0288Ksp = [Pb2+][Br]2 = (0.0144)(0.0288)2 = 1.19 x 10-5

*Example3.5Calculating Molar Solubilityfrom Ksp

*Example 3.5:Calculate the molar solubility of BaSO4. Ksp = 1.07 x 10-10 at 25 C

*

*Write down the given quantity and its units.

Given:Ksp = 1.07 x 10-10Example:Calculate the molar solubility of BaSO4. Ksp = 1.07 x 10-10 at 25 C

*

*Write down the quantity to find and/or its units.

Find: molar solubility, M

Information:Given:Ksp = 1.07 x 10-10Example:Calculate the molar solubility of BaSO4. Ksp = 1.07 x 10-10 at 25 C

*

*Collect needed equations:

BaSO4(s) Ba2+(aq) + SO42-(aq)Ksp = [Ba2+][SO42-]Information:Given:Ksp = 1.07 x 10-10Find: [BaSO4], Mbecause for each BaSO4 dissolved you produce one Ba2+:[BaSO4] = [Ba2+] = [SO42-]Example3.5:Calculate the molar solubility of BaSO4. Ksp = 1.07 x 10-10 at 25 C

*

*Write a solution map:

Ksp[Ba2+]Information:Given:Ksp = 1.07 x 10-10Find: [BaSO4], M = [Ba2+] = [SO42-]Equation: Ksp = [Ba2+][SO42-]Example 3.5:Calculate the molar solubility of BaSO4. Ksp = 1.07 x 10-10 at 25 CKsp = [Ba2+][SO42-]

*

*Apply the solution map:

Information:Given:Ksp = 1.07 x 10-10Find: [BaSO4], M = [Ba2+] = [SO42-]Equation: Ksp = [Ba2+][SO42-]Solution Map: Ksp [Ba2+]Example 3.5:Calculate the molar solubility of BaSO4. Ksp = 1.07 x 10-10 at 25 C

*

*Check the answer:

Information:Given:Ksp = 1.07 x 10-10Find: [BaSO4], M = [Ba2+] = [SO42-]Equation: Ksp = [Ba2+][SO42-]Solution Map:Ksp [Ba2+]Example 3.5:Calculate the molar solubility of BaSO4. Ksp = 1.07 x 10-10 at 25 CThe molar solubility of BaSO4 is 1.03 x 10-5 M.The units, M, are correct.The magnitude makes sense as BaSO4 is classified insoluble, so its solubility should be very small.

*

*Combustion as Redox2 H2(g) + O2(g) 2 H2O(g)

*

Tro, Chemistry: A Molecular Approach*Redox without Combustion2 Na(s) + Cl2(g) 2 NaCl(s)2 Na 2 Na+ + 2 eCl2 + 2 e 2 Cl

Tro, Chemistry: A Molecular Approach*

*Reactions of Metals with Nonmetalsconsider the following reactions:

4 Na(s) + O2(g) 2 Na2O(s)2 Na(s) + Cl2(g) 2 NaCl(s)the reaction involves a metal reacting with a nonmetalin addition, both reactions involve the conversion of free elements into ions

4 Na(s) + O2(g) 2 Na+2O (s)2 Na(s) + Cl2(g) 2 Na+Cl(s)

*

*Oxidation and Reductionin order to convert a free element into an ion, the atoms must gain or lose electrons

of course, if one atom loses electrons, another must accept themreactions where electrons are transferred from one atom to another are redox reactionsatoms that lose electrons are being oxidized, atoms that gain electrons are being reduced

2 Na(s) + Cl2(g) 2 Na+Cl(s)Na Na+ + 1 e oxidationCl2 + 2 e 2 Clreduction

*

*Electron Bookkeepingfor reactions that are not metal + nonmetal, or do not involve O2, we need a method for determining how the electrons are transferredchemists assign a number to each element in a reaction called an oxidation state that allows them to determine the electron flow in the reaction

even though they look like them, oxidation states are not ion charges!oxidation states are imaginary charges assigned based on a set of rules ion charges are real, measurable charges

*

*Rules for Assigning Oxidation Statesrules are in order of priority

free elements have an oxidation state = 0Na = 0 and Cl2 = 0 in 2 Na(s) + Cl2(g)monatomic ions have an oxidation state equal to their chargeNa = +1 and Cl = -1 in NaCl (a) the sum of the oxidation states of all the atoms in a compound is 0Na = +1 and Cl = -1 in NaCl, (+1) + (-1) = 0

*

*Rules for Assigning Oxidation States(b) the sum of the oxidation states of all the atoms in a polyatomic ion equals the charge on the ionN = +5 and O = -2 in NO3, (+5) + 3(-2) = -1(a) Group I metals have an oxidation state of +1 in all their compoundsNa = +1 in NaCl

(b) Group II metals have an oxidation state of +2 in all their compoundsMg = +2 in MgCl2

*

*Rules for Assigning Oxidation Statesin their compounds, nonmetals have oxidation states according to the table belownonmetals higher on the table take priority

NonmetalOxidation StateExampleF-1CF4H+1CH4O-2CO2Group 7A-1CCl4Group 6A-2CS2Group 5A-3NH3

*

*Practice Assign an Oxidation State to Each Element in the followingBr2K+LiFCO2SO42-Na2O2

*

*Practice Assign an Oxidation State to Each Element in the followingBr2 Br = 0, (Rule 1)K+K = +1, (Rule 2)LiFLi = +1, (Rule 4a) & F = -1, (Rule 5)CO2O = -2, (Rule 5) & C = +4, (Rule 3a)SO42- O = -2, (Rule 5) & S = +6, (Rule 3b)Na2O2 Na = +1, (Rule 4a) & O = -1, (Rule 3a)

*

*Oxidation and ReductionAnother Definitionoxidation occurs when an atoms oxidation state increases during a reactionreduction occurs when an atoms oxidation state decreases during a reaction

CH4 + 2 O2 CO2 + 2 H2O-4 +1 0 +4 2 +1 -2

*

*OxidationReductionoxidation and reduction must occur simultaneously

if an atom loses electrons another atom must take them the reactant that reduces an element in another reactant is called the reducing agent

the reducing agent contains the element that is oxidizedthe reactant that oxidizes an element in another reactant is called the oxidizing agent

the oxidizing agent contains the element that is reduced2 Na(s) + Cl2(g) 2 Na+Cl(s)Na is oxidized, Cl is reducedNa is the reducing agent, Cl2 is the oxidizing agent

*

*Identify the Oxidizing and Reducing Agents in Each of the Following3 H2S + 2 NO3 + 2 H+ 3 S + 2 NO + 4 H2OMnO2 + 4 HBr MnBr2 + Br2 + 2 H2O

*

*Identify the Oxidizing and Reducing Agents in Each of the Following3 H2S + 2 NO3 + 2 H+ 3 S + 2 NO + 4 H2OMnO2 + 4 HBr MnBr2 + Br2 + 2 H2O+1 -2 +5 -2 +1 0 +2 -2 +1 -2ox agred ag+4 -2 +1 -1 +2 -1 0 +1 -2red agox ag

*

*OxidationReduction ReactionsWe say that the element that loses electrons in the reaction is oxidized. And the substance that gains electrons in the reaction is reduced.You cannot have one without the other.In combustion, the O atoms in O2 are reduced, and the non-O atoms in the other material are oxidized.

*Combustion as RedoxIn the following reaction:

2 Mg(s) + O2(g) 2 MgO(s)The magnesium atoms are oxidized.

Mg0 Mg2+ + 2 eThe oxygen atoms are reduced.

O0 + 2 e O2

*Combustion as Redox, ContinuedEven though the following reaction does not involve ion formation, electrons are still transferred.

CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g)The carbon atoms are oxidized.

C4 C+4 + 8 eThese are not charges, they are called oxidation numbers, but they help us see the electron transfer.The oxygen atoms are reduced.

O0 + 2 e O2

*Bonding Theoriesexplain how and why atoms attach togetherexplain why some combinations of atoms are stable and others are not

why is water H2O, not HO or H3Oone of the simplest bonding theories was developed by G.N. Lewis and is called Lewis TheoryLewis Theory emphasizes valence electrons to explain bondingusing Lewis Theory, we can draw models called Lewis structures that allow us to predict many properties of molecules

aka Electron Dot Structuressuch as molecular shape, size, polarity

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*Why Do Atoms Bond?processes are spontaneous if they result in a system with lower potential energychemical bonds form because they lower the potential energy between the charged particles that compose atomsthe potential energy between charged particles is directly proportional to the product of the chargesthe potential energy between charged particles is inversely proportional to the distance between the charges

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*Potential Energy Between Charged Particles0 is a constant

= 8.85 x 10-12 C2/Jmfor charges with the same sign, Epotential is + and the magnitude gets less positive as the particles get farther apartfor charges with the opposite signs, Epotential is and the magnitude gets more negative as the particles get closer togetherremember: the more negative the potential energy, the more stable the system becomes

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*Potential Energy BetweenCharged Particles

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*Bondinga chemical bond forms when the potential energy of the bonded atoms is less than the potential energy of the separate atomshave to consider following interactions:

nucleus-to-nucleus repulsionelectron-to-electron repulsionnucleus-to-electron attraction

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*Types of Bonds

Types of AtomsType of BondBond Characteristicmetals to nonmetalsIonicelectronstransferrednonmetals tononmetalsCovalentelectrons sharedmetal tometalMetallicelectronspooled

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*Electronegativitymeasure of the pull an atom has on bonding electronsincreases across period (left to right) anddecreases down group (top to bottom)

fluorine is the most electronegative elementfrancium is the least electronegative elementthe larger the difference in electronegativity, the more polar the bond

negative end toward more electronegative atom

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*Electronegativity Scale

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Introductory Chemistry, 2nd Edition Nivaldo Tro

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Transcript of Introductory Chemistry, 2nd Edition Nivaldo Tro