Here are the types of reactions and balanced equations for the examples given: 1. Single displacement: Cu + 2AgNO3 → 2Ag + Cu(NO3)2 2. Double displacement: Pb(NO3)2 + 2KI → PbI2 + 2KNO3 3. Combustion: CH4 + 2O2 → CO2 + 2H2O 4. Decomposition: ZnCO3 → ZnO + CO2 5. Combination: 2Mg + O2 → 2MgO 6. Combination: Zn + O2 → ZnO

1. YEAR 10 SCIENCE 2012 – CHEMISTRY UNIT

2. Types of reactions
• There are five main types of chemical reactions we
will talk about:
1) Combination reactions
2) Decomposition reactions
3) Single displacement reactions
4) Double displacement reactions
5) Combustion reactions
• You need to be able to identify the type of reaction
and predict the product(s)

3. Types of reactions
• Some steps for doing reactions
1) Identify the type of reaction
2) Predict the product(s) using the type of reaction
as a model
3) Write a worded equation for the reaction
4) Balance it –the formulae & the equation
• Don’t forget to check the states of matter:
• (s) = solid; (l) = liquid; (g) = gas;
• (aq) = aqeous = soluble salt dissolved in water

4. COMBINATION reactions
• Combination reactions occur when two substances
(generally elements) combine and form a compound.
• Sometimes these are called synthesis or addition
reactions.
reactant + reactant  1 product
A + B  AB
• Example: 2H2 + O2  2H2O
• Example: C + O2  CO2

5. COMBINATION reactions

6. COMBINATION reactions
• Predict the products. Write and balance the
following synthesis reaction equations.
• Sodium metal reacts with chlorine gas
• Solid Magnesium reacts with fluorine gas
• Aluminum metal reacts with fluorine gas

7. DECOMPOSITION reactions
• Decomposition reactions occur when a compound
breaks up into the elements or in a few to simpler
compounds
1 reactant  product + product
AB  A + B
• Example: 2 H2O  2H2 + O2
• Example: 2 HgO  2Hg + O2

8. DECOMPOSITION reactions

9. DECOMPOSITION reactions
• Predict the products. Then, write and balance the
following decomposition reaction equations.
• Solid Lead (IV) oxide decomposes
• Aluminum nitride decomposes

10. SINGLE DISPLACEMENT
reactions
• Single Displacement Reactions occur when one
element replaces another in a compound.
• Two displacements are possible:
• a metal can replace a metal (+ ions)
• a non-metal can replace a non-metal (- ions).

11. SINGLE DISPLACEMENT
reactions
element + compound  element + compound
A + BC  AC + B (if A is a metal)
A + BC  BA + C (if A is a non-metal)

12. SINGLE DISPLACEMENT
reactions

13. SINGLE DISPLACEMENT
reactions
• Write and balance the following single replacement
reaction equation:
• Zinc metal reacts with aqueous hydrochloric acid
• Sodium chloride solid reacts with fluorine gas
• Aluminum metal reacts with aqueous copper (II)
nitrate

14. Double DISPLACEMENT
reactions
• Double Replacement Reactions occur when a metal
replaces a metal in a compound and a non-metal
replaces a non-metal in a compound
Compound + compound  compound+ compound
AB + CD  AD + CB

15. DOUBLE DISPLACEMENT
reactions
• Example:
• Solid sodium chloride is dissolved into silver nitrate
solution:
AgNO3 (aq) + NaCl (s)  AgCl (s) + NaNO3 (aq)
• Another example:
• Two solutions of potassium sulfate and barium
nitrate are mixed together:
K2SO4 (aq) + Ba(NO3)2 (aq)  2 KNO3 (aq) + BaSO4 (s)

16. DOUBLE DISPLACEMENT
reactions
• Predict the products. Balance the equations:
1. Hydrochloric acid + silver nitrate
2. Calcium chloride + sodium phosphate
3. Lead (II) nitrate + barium chloride
4. Iron (III) cholride + sodium hydroxide
5. Sulfuric acid + sodium hydroxide
6. Potassium hydroxide + copper sulfate

17. Combustion reactions
• Combustion reactions occur when a hydrocarbon
reacts with oxygen gas.
• This is also called burning!!!
• In order to burn something you need the 3 things in
the “fire triangle”:
1) A Fuel (hydrocarbon)
2) Oxygen to burn it with
3) Something to ignite the
reaction (spark)

18. Combustion reactions
• In general:
CxHy + O2  CO2 + H2O
• Products in combustion are ALWAYS carbon dioxide
and water. (although incomplete burning does cause
some by-products like carbon monoxide)
• Combustion is used to heat homes and run
automobiles (octane, as in gasoline, is C8H18)

19. Combustion reactions
• Example
• pentane (C5H12) + O2  CO2 + H2O
• Write the products of the following combustion
reaction:
• Combustion of decane

20. CORROSION reactions
• Type of combination reaction.
• Oxygen combines with a metal to form an ionic
compound.
metal + O2  metal oxide

21. Precipitation reactions
• Type of double displacement reaction.
• Two solutions of soluble salts are mixed, resulting in
an insoluble solid (precipitate) forming.
Soluble salt A + Soluble salt B
(aq) (aq)
 precipitate + Soluble salt C
(S) (aq)

22. Precipitation reactions
• Solubility rules are needed to work out whether a
precipitate will form.
Form a soluble compound when Form an insoluble compound
Ions
joined with these ions when joined with these ions
Sodium, Ammonium,
Potassium, Lithium, All None
Nitrate
Chloride, Silver
Bromide, All (with exceptions) Mercury
Iodide Lead
Barium
Sulphate All (with exceptions) Lead
Calcium
Sodium
Carbonate, Phosphate Ammonium
All (with exceptions)
and Hydroxide Potassium
Lithium

23. Neutralisation reaction
• Type of double displacement reaction.
• An acid and a base react with each other.
• Generally, the product of this reaction is a salt and
water.
acid + base  salt + water

24. Acid + metal reaction
• Type of single displacement reaction.
• An acid and a metal react with each other.
• Generally, the product of this reaction is a salt and
hydrogen gas.
acid + metal  salt + H2

25. Acid + metal carbonate
reaction
• An acid and a metal carbonate react with each other.
• Generally, the product of this reaction is a salt, water
and carbon dioxide gas.
acid + metal carbonate
 salt + H2O + CO2

26. PRACTICE
Identify the type of reaction and try to write a
correctly balanced chemical equation for each of the
following reactions:
 Copper + silver nitrate  silver + copper nitrate
 Lead nitrate + potassium iodide  lead iodide +
potassium nitrate
 Methane gas + oxygen  carbon dioxide + water
 Zinc carbonate  zinc oxide + carbon dioxide
 Magnesium + oxygen  magnesium oxide
 Corrosion of zinc