Reactions With Redox

8/11/2019 Reactions With Redox

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REACTIONSREACTIONS


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Im not sure

how to reactto that

And the punsbeginI got my ionyou.


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Solutions where water is the dissolvingSolutions where water is the dissolving

mediummedium

The chemical processes occuring inThe chemical processes occuring inaqueous solutions are of the three majoraqueous solutions are of the three major

types: precipitation reactions, acid-basetypes: precipitation reactions, acid-base

reactions, and redox reactionsreactions, and redox reactions

Vocab check!Solutions:Homogenous mixture of two ormore substances

Solvent:The component that is present in

greater quantity

Solutes:Dissolved in the solvent

Example: If Josh SandofAll had somesodium chloride and dissolved it in a large

amount of water, then the water is thesolvent, and the sodium chloride is the

solute.

Get it?

Sometimes me andchem just dontMIX.

Aqueous solutionsAqueous solutions


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Solubility rulesSolubility rulesSolubility is defined as theSolubility is defined as the

ability to dissolve in solution.ability to dissolve in solution.

Pretty simple right?Pretty simple right?

Some substances areSome substances are

categorized as soluble orcategorized as soluble or

insoluble.insoluble.


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Butwhatssolubleand whatsinsoluble?


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The following compounds willdissolve in solution:

NH4-, Li+, Na+, K+, Rb+, Cs+, Fr+

NO3-, ClO4-, ClO3-, C2H3O2-

Cl-, Br-, I-(EXCEPT w/ Ag+, Pb2+,

Hg2+

)

SO42-(EXCEPT w/ HG2+, Pb2+,Sr2+, Ca2+, Ba2+)

SolublesSolubles


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The following compounds willnot dissolve in solution

OH-(EXCEPT w/ Li+, Na+,

K+

, Rb+

, Cs+

, Fr+

, Ca2+

, Sr2+

,Ba2+)

PO43-

, S2-

, CO32-

, SO32-

(EXCEPT w/ NH4+, Li+, Na+,

K+, Rb+, Cs+, Fr+)

InsolublesInsolubles


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POPPOP

QUIZQUIZ

IS THE FOLLOWING

SOLUBLE..

NaCKOHKOHAgClAgCl


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ElectrolytesElectrolytes

Electrolytes are salts that conduct electricity.Electrolytes are salts that conduct electricity.Most electrolytes are also ions. Here are aMost electrolytes are also ions. Here are afew examples:few examples:

Na+ SodiumNa+ Sodium

K+ PotassiumK+ Potassium

HCO3- bicarbonateHCO3- bicarbonate

Cl- ChlorideCl- Chloride

SO42- SulfateSO42- SulfatePO42- PhosphatePO42- Phosphate

Mg2+ MagnesiumMg2+ Magnesium


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Strong/Weak Acids and Bases

A conjugate base isthe ion or molecule

left after an acid haslost a hydrogen.

The lowerthepKa, the stronger

the acid.


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Acid, Base, Neutralization and Salts

Acids ionize producing H+ions in water

Bases ionize producing OH-ions in waterWhen an acid and base have a babychild, a Neutralizationreaction occurs!! This product, or babychild if you will,doesnt look anything like its parent reactants.

HCl(aq) + NaOH(aq) H2O(l) +NaCl(aq)

A salt is any ionic compound whose cation comesfrom a base.

ThatsBASICallyhow thatworks.


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Moles/1 Liter of SolutionMoles/1 Liter of Solution

Way to quantify concentrationWay to quantify concentration

The concentration is the amount of solute dissolvedThe concentration is the amount of solute dissolvedin a given quantity of solvent or solution.in a given quantity of solvent or solution.

So basically, the more solute dissolved the moreSo basically, the more solute dissolved the more

concentrated the resulting solution is.concentrated the resulting solution is.

The process of using water to manipulate molarity isThe process of using water to manipulate molarity is

called dilution.called dilution.

MolarityMolarityHey Dani, Imhaving a problemrememberingthis stuff.

Im sure I canfigure out aSOLUTION if ICONCENTRATE hard enough.


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Titration Titration is used to determine the concentration of a

particular solute.

A reagent, called a standard solution, is added until justthe point where all of the unknown solution has reacted

(the equivalence point). Then stoichiometry is used todetermine the concentration of the unknown solution.

*Remember: A solute is a substance dissolved in asolution and a reagent is a substance added to a

solution to see if a reaction occurs.

Think the Permanganate Lab!


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Ionic compounds are formed by a cation andanion (metal and nonmetal). For example:

Cation- Na + Anion- Cl will form NaCl

Molecular compounds are formed by covalentbonds (sharing electrons) between nonmetals.

For example:Nonmetal- C + other nonmetal- O will form CO2

by sharing electrons to allow the atoms to reach

a stable octet.

Ionic and molecularIonic and molecular

compoundscompounds

You know,Cations arePAWSitive.


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Precipitation Reaction

Reactions that result in the formation of aninsoluble solid (precipitate).

A precipitate reaction will occur when pairsof oppositely charged ions attract eachother so strongly that they form insolubleions.

BaCl2(aq) + Na2SO4(aq) BaSO4(s) +2NaCl(aq)


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Percent solutionPercent solution

Percent of a substance in a solution can befound by either mass or volume.

The formula for either is (mass or volume ofsubstance/ total mass or volume ofsolution)*100

35gX/75gTs=0.47

0.47*100= 47% solution of substance X in solution Ts is 47%

What did you get on

your reactions testanyway?

None of your Bismuth!


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Empirical formula

Empirical formula is the smallest unit that a molecule orcompound is found in.

To find Empirical Formula, use these steps:

Assume that there is 100g of substanceUse the given percentages and convert them moles

Divide each molar value by the smallest one andround each quotient to eh nearest whole number

If answers are too far to round, multiplyto get closer


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Empirical formula cont.

Consider a compound that was 57.14% C, 6.16% H,9.52% N, 27.18% O.

Assume 100g- 57.12g C, 6.16g H, 9.52g N, 27.18g O.

Convert to moles- 4.67mol C, 6.15mol H, 0.68mol N,1.70mol O.

Divide by 0.68- C=7, H=8.97/9, N=1, O=2.5

Oxygen is too far to round so multiply by 2

C14H18N2O5


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Writing equations

A Chemical Equation is a symbolicrepresentation of a chemical reaction thatreveals 3 things: reactants, products, and

mole ratios.

Symbols:

(g) = gas, (l)=liquid, (s)=soluble,(aq)=aqueous

Oh snapdang.This part is easy.

I know WRITE? ItsSODIUM easycompared to someof the other stuff

we do.

Got any othersodium jokes?

Na.


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Example

Aluminum reacts with phosphoric acid toyield hydrogen gas and aluminumphosphate.

2Al + 2H2Al + 2H33POPO44 3H2 + 2AlPO 3H2 + 2AlPO44


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Balancing

Balancing equations is the act of confirming that theamount of reactants is equal to the products. Make surethat you do not change subscripts to balance. You mayonly change the coefficients.

Consider Ca + PO4 Ca 3(PO4)2

Use coefficients to match up the number of ions

Answer 2Ca +2PO4 Ca 3(PO4)2


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HOFBrNCl

The acronym HOFBrINCl shows all of thediatomic molecules on the periodic table

H, O, F, Br, I, N, & Cl are all written withsubscripts of 2 when not bonded to anotherelement because none of these exist innature in a single molecule.

In the equation: 2H2O----> O2 + 2H2 oxygenand hydrogen both have subscripts of 2.

You betterrememberthese.Or else.


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Types of Reactions:Types of Reactions:

SynthesisSynthesis DecompositionDecomposition Single ReplacementSingle Replacement Double ReplacementDouble Replacement RedoxRedox

(Oxidation/Reduction)(Oxidation/Reduction) CombustionsCombustions


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METALS + NONMETALS binarySALT

6Li + N22Li3N

Metallic Oxides + water Bases(metallic hydroxides)

Na2O + HOH 2NaOH

Nonmetallic Oxides + water Acids

CO2+ H2O H2CO3

Metallic Oxides + Nonmetallic Oxides Salts

Na2O + CO2Na2CO3

SynthesisSynthesis


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Decomposition

Many decomposition reaction predictions are based on thepolyatomic ion.

Metallic Chlorates Metallic Chlorides and Oxygen Gas

Mg(ClO3)2 MgCl2+ 3O2

Metallic Carbonates Metallic Oxides and Carbon Dioxide

MgCO3 MgO + CO2

Ammonium Carbonate Ammonia, water and carbon dioxide

(NH4)2CO3 2NH3+ H2O + CO2

Wanna hear a joke about NitricOxide?!

NO


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Decomposition Continued

Binary Compound 2 Elements

2NaCl Cl2

Hydrogen Peroxide (H2O2) water and Oxygen

H2O2 H2O + O2Ammonium Hydroxide Ammonia, water, and CarbonDioxide

H2CO3 H2O + CO2


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Decomposition Reactions Acids

Sulfurous Acid Sulfur Dioxide and water

H2SO3 H2O + SO2

Carbonic Acid Carbon Dioxide and water

H2CO3 H2O + CO2


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Single ReplacementSingle Replacement

Single replacement reactions occur when oneelement or ion takes the place of another in acompound.

An element will replace another in acompound if it is more reactive than theelement or ion it wants to replace.


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Common Single Replacement ReactionsCommon Single Replacement Reactions

Active Metal replaces less Active Metal from compound in

aqueous solution

3Mg + 2FeCl3 2Fe + 3MgCl2

Active Metal replaces Hydrogen in water

2Na + 2HOH H2+ 2NaOH

Active Metal replaces Hydrogen in Acids

2Li + 2HCl H2+ 2LiCl

Active Nonmetals replace less Active Nonmetals from

compound in aqueous solutionCl2+2KI I2+ 2KCl

Just zincabout it


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Replacement Reaction in which all ions switchpartners:

AX + BY AY +BX

Process:Determine which ions are presentWrite the formulas of the products by combining the cation of thereactant with the anion of the other reactant *Remember to useionic charges to determine subscripts*

Check solubility rules, in precipitate reactions, at least oneproduct must be insolubleDont forget to balance! :)

NaCl(aq) +AgNO3(aq) AgCl(s) +NaNO3(aq)

Metathesis (DoubleMetathesis(Double

Replacement)Replacement)


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The steps:1. Assign each element oxidation numbers!

2.Figure out which is being oxidized, and which is reduced. Remember, thesubstance being reduced is the one that gains electrons(more negative),and the one oxidized loses electrons (less negative).

3. Separate the single equation, into two simpler equations. One equationshould have the substance being oxidized, and the other equation

showing the substance reduced.

4. First start with one of the equations. (Youll repeat with the other equationafterwards). Balance the equation by adding the appropriate amount ofelectrons to whichever side it is needed.

REDOXXXXXXXXX!

INACIDSAssigningOxidationNumbers:PureElement=0Hydrogen=+1(ExceptHydride

swhichare-1)Oxygen=-2(Exceptinperoxidewhereitis-1)

-Thesumofallatomsoxidation

numbersistheequaltothechargeontheparticle


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5.Since were dealing with an acidic solution, we balance the elementsin the reaction by adding H2O and H

+. On the side of the half reaction

that needs Oxygen, you add the H2O. Then you add the H+to the

other side to balance out the hydrogens. Its all about the balance yo.

6.Now that one of your half reactions is balanced, do the same exactthing to the other one.

7.Now, with both of your equations. You want the amount of electronsto be the same in both of them. So, you can multiply the halfreactions by a number in order to make it the same. For example, ifyou have your first equation with 4 added electrons, and your secondone you added 6, then you can multiply the entire first equation by 3,and the second by 2 so that the electrons equal 12 in both half

reactions.

8.Add the two half reactions together. All reactants go on one side, andthe products on the right side.

9.Cancel out anything that is on both sides.

CC


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CC

OO

NN

FF

UUSS

EEDD

??

EXAMPLETIME

InanacidicSolution


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MnMn2+2++ BiO+ BiO33-- Bi Bi3+3+++

MnOMnO44--

In an acidic Solution.

1. Oxidation numbers!1. Oxidation numbers!

+2+2 +7+7+5+5 +3+3

Because theMn has acharge ofpositive 2

Because Oxygen has anoxidation number of -2.There are three of them,so thats a total of -6.

However the total charge isa -1. Therefore oxidation

number of Bi is +5.

Because Bihas acharge of+3

Because Oxygensox. number is -2, andthere are four of

them, making it a totalof -8. However thetotal charge is a -1, so

the Mn must be +7.

The Bi is being reduced, becauseThe Bi is being reduced, because

it gains electrons, or decreases init gains electrons, or decreases in

its oxidation number.its oxidation number.

The Mn is being oxidized because itThe Mn is being oxidized because it

loses electrons, or increases inloses electrons, or increases in

its oxidation number.its oxidation number.

Now you form

your two half

reactions.

In an acidic Solution.


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MnMn2+2++ BiO+ BiO33-- Bi Bi3+3+++

MnOMnO44--Reduced:Reduced:

BiOBiO33-- Bi Bi3+3+

+2 +7+5 +3

Since the left has a charge of +5,we add 2 electrons to that sideSince the left has a charge of +5,we add 2 electrons to that sideto equal the +3 charge on the left, because 5+ (-2) = +3to equal the +3 charge on the left, because 5+ (-2) = +3

2e2e--++Now that we have the charges balanced, we need to balance our

elements. There is one Bi on the right, and one Bi on the left. We dontneed to do anything there. However, there are 3 Os on the left, and noneon the right. To fix this, we add 3H2O to the right since we are dealing

with an acidic solution.

+3H+3H2200

However, now we have 6 H on the right, and none on the left. To fixthis, we simply add 6H+to the left. Now there are 6 Hs on both sidesmaking our reaction nice and balanced.

6H6H++++

Oxidized:Oxidized:

Now you try with theNow you try with the

oxidized equationoxidized equationMnMn2+2+

MnOMnO44--

+5e+5e--

4H4H22O+O+ +8H+8H++

Now we have our two reactions. Our next step is to get ourelectrons that we added, to be the same. Right now we have a 2e-on our reduced formula, and a 5e- on our oxidized. So, well

multiply the entire first formula by 5, and the second by 2, so theelectrons will be 10 on both.

Reduced:Reduced:


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2e2e--+ 6H+ 6H+++ BiO+ BiO33-- Bi Bi3+3++ 3H+ 3H22O]O]X5X5

10e10e--+ 30H+ 30H+++ 5BiO+ 5BiO33-- 5Bi5Bi3+3+++15H15H22OO

Reduced:Reduced:

Oxidized:Oxidized:

[4H4H22O + MnO + Mn2+2+ MnO MnO44--+ 5e+ 5e--+ 8H+ 8H++]]X2X28H8H22O + 2MnO + 2Mn

2+2+2MnO2MnO44--+ 10e+ 10e--++

16H16H++Now we add themNow we add them

togethertogether

10e-+ 30H++ 5BiO3-+ 8H2O + 2Mn+

2+ 5Bi3++ 15H2O + 2MnO4-+ 10e-

+ 16H+

Cancel out whats on bothCancel out whats on both

sidessides14H+

+ 5BiO3-

+ 2Mn2+

5Bi3+

+ 7H2O +2MnO4

-


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In Basic solutions, you do the EXACT sameIn Basic solutions, you do the EXACT same

steps, plus one more. In basic,steps, plus one more. In basic,

you add OH- instead of H+ though.you add OH- instead of H+ though.

Al + MnOAl + MnO44-- MnO MnO22++

Al(OH)Al(OH)44--

0 +3+7 +4

Oxidation:Oxidation:

Al Al(OH)4-+ 3e-4OH-+Reduction:Reduction:

3e-

+ MnO4-

MnO2-

+2H+2H22OO4H4H++

++ +4OH+4OH--

OHOH--

++

Since there are4 OH-on theright you addOH-to the left.

We add 4OH- becausewe added 4H+The 4OHThe 4OH

--and 4Hand 4H++

come 4Home 4H22O, which weO, which we

ancel with the 2Hancel with the 2H22OO

On the other side.On the other side.

2H2H22O + 3eO + 3e--+ MnO+ MnO44

-- MnO MnO22--+ 4OH+ 4OH--

ADDTHEMTOGETHERADDTHEMTOGETHER


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4OH-+ Al + 2H2O + 3e-+ MnO4- Al(OH)4-+3e-+ MnO2-

+4OH-

Al + 2H2O + MnO4- Al(OH)4

-+

MnO2-

Cancel whats on both sidesCancel whats on both sides


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Combustion

A combustion reaction occurs when acompound combines with Oxygen toform Carbon Dioxide and water.

C2H5OH + 3O2 2CO2+ 3H2O


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Id say one last pun, butall of the good onesArgon.

TheTheENDEND

Reactions With Redox

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