Types of Chemical Reactions

Chapter 6

6 Types

• Synthesis• Decomposition• Single displacement• Double displacement• Combustion• Neutralization (Chapter 5)

Online Resources

• Animation: http://www.youtube.com/watch?v=tE4668aarck

• DEMOS:http://www.youtube.com/watch?v=i-HHvx1VC_8• Lessons: • http://www.youtube.com/watch?v=g-

biRwAVTV8 (Flintstones)• http://www.youtube.com/watch?

v=3vLAH4Py9zI

Synthesis

• This type of reaction involves the combination of multiple reactants into a single product

• Synthesis reactions have a general formula:

F + W FW➜

Examples1. Element + Element Compound➜ 2Al(s) + 3Cl2 (g) 2 AlCl➜ 3 (s)

2. Compound + Element Compound➜

PCl3(l) + Cl2 (g) PCl➜ 5 (s)

3. Compound + Compound Compound➜ SO2(g) + H2O(l) H➜ 2SO4(aq)

Decomposition

• This type of reaction involves the splitting of a single reactant into multiple products

• Decomposition reactions have the general formula:

FW F +W➜

Examples1. Compound Element ➜ + Element 2HI(g) H➜ 2 (g) + I2 (g)

2. Compound Compound ➜ + Element 2 H2O2(l) 2H➜ 2O(l) + O2 (g)

3. Compound Compound ➜ + Compound

Ca(OH)2(s) CaO(s) ➜ + H2O(l)

WORK

• Read section 6.1

• Worksheet

• Page 226 to 227, ALL Practice Problems:

• Review Questions: Page 229 #1-10

Single Displacement• This type of reaction involves an element and a

compound as reactants• The element displaces (replaces) one of the

elements in the compound• cations replace cations, anions replace anions • Single displacement reactions have the general

formula: FW + B FB + W➜

ExamplesElement + Compound Element + Compound

Zn(s) + CuSO4(aq) Cu (s) + ZnSO4(aq)

Mg(s) + 2AgNO3 (aq) 2Ag (s) + Mg(NO3)2(aq)

Br2(g) + CaI2(aq) I2 (g) + CaBr2(aq)

2 Na(s) + 2 H2O(l) H2 (g) + 2 NaOH(aq)

2 Na + 2 HOH H2 + 2 NaOH

Double Displacement• This type of reaction involves two

compounds as reactants• Positive and negative ions in two compounds

appear to “change partners” to form two new compounds with no change in oxidation numbers [ie. Copper (II) stays copper (II)].

• Double displacement reactions have the general formula: FW + RB FB + RW

ExamplesCompound + Compound Compound + Compound

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

2H3PO4 (aq) + 3 Ca(OH)2 (aq) Ca3(PO4)2 (s) + 6H2O (l)

MnS(s) + 2HCl(aq) MnCl2 (aq) + H2S(g)

WORK

• Read pages 233 to 236

• Finish Worksheet

• Page 233 to 235, ALL Practice Problems

• Review Questions: Page 240 #1-12

Combustion

• Combustion is a very rapid reaction of a substance with oxygen to produce compounds called oxides.

• We often call this process burning.• The following word equation represents a

general combustion reaction:fuel + oxygen oxides + (energy)

O2 heat and light

Hydrocarbons

• Hydrocarbons (compounds with H, C) are the most important fuels that we burn! Gasoline, natural gas (methane), propane, kerosene and matches.

• When these burn, the products are mostly CO2 and H2O which are released into the atmosphere. These can contribute to the green house effect.

Common HydrocarbonsFORMULA COMMON

NAMECHEMICAL

NAME

CH4 Methane Carbon tetrahydride

C3H8 Propane Tricarbonoctahydride

C4H10 Butane Tetracarbondecahydride

Burning Propane

• Complete combustionPropane + oxygen carbon dioxide + waterC3H8 + 5O2 3CO2 + 4H2O

• Incomplete combustionPropane + oxygen carbon dioxide + water + carbon monoxide + carbon

2C3H8 + 7O2 2CO2 + 8H2O + 2CO + 2C

Complete vs. Incomplete Combustion of Hydrocarbons

• Complete combustion:– Occurs when the right amount of O2 is available to react with the

fuel and all the carbon in the fuel is converted into CO2.– The only products are CO2 and H2O.

• Incomplete combustion:– This occurs when there is not enough oxygen available to react

with the fuel – four products are produced instead of two: CO2, CO, C, H2O– Carbon monoxide is a colourless, odourless, and poisonous gas

that can can combine with the haemoglobin in the blood to starve the body of oxygen and cause death!!!

– Carbon is the black residue (soot) that you see in fireplaces.

Combustion of metals

• 2 Ca + O2 2 CaO • Combustion & synthesis

Combustion of Non-metals

• N2 + 2 O2 2 NO2 • Combustion & synthesis

Homework

• Read pages 230 to 232• Page 240 # 9 & 11• Page 242 # 11 & 13

Neutralization• A neutralization reaction is a special case of double

displacement reaction between an Acid and a Base. The products of a neutralization reaction are always water and a salt (ionic compound).

• Examples:1. HCl(aq) + NaOH(aq) HOH + NaClHydrochloric acid + sodium hydroxide water + sodium chloride2. H2SO4(aq) + 2KOH 2H2O + K2SO4

Sulfuric acid + potassium hydroxide water + potassium sulfate• During a neutralization reaction, the hydrogen ion from

the acid reacts with the hydroxide ion from the base H+ + OH- H2O

Homework

• Read Section 5.2• Worksheet