How to Balance Chemical Equations
This is part of Year 11 HSC Chemistry course under the topic of Chemical Reactions and Stoichiometry
HSC Chemistry Syllabus
- Relate stoichiometry to the law of conservation of mass in chemical reactions by investigating:
- Balancing chemical equations (ACSCH039)
- Solving problems regarding mass changes in chemical reactions (ACSCH046)
How to Balance Chemical Equations
What Are Chemical Equations? (Recap)
A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae. They describe a chemical change which occurs as a result of chemical reaction.
Balancing Chemical Equations (Answers in Video)
Example 1 – Synthesis
Balance the following equation for synthesis of water.
$$ H_2(g) + O_2(g) \rightarrow H_2O(l)$$
Example 2 – Synthesis
Balance the following equation for the synthesis of ammonia.
$$ N_2(g) + H_2(g) \rightarrow NH_3(g)$$
Example 3 – Precipitation
Balance the following equation for the precipitation of calcium sulfate.
$$CaBr_2(aq) + K_2SO_4(aq) \rightarrow KBr(aq) + CaSO_4(s)$$
Example 4 – Neutralisation
Balance the following equation for the neutralisation between lead(II) hydroxide and hydrochloric acid.
$$Pb(OH)_2(s) + HCl(aq) \rightarrow H_2O(l) + PbCl_2(aq)$$
Example 5 – Incomplete Combustion
Balance the following equation for the incomplete combustion of octane. (There are more than one correct answer for this reaction)
$$C_8H_{18}(l) + O_2(g) \rightarrow CO_2(g) + CO(g) + H_2O(g)$$
Example 6 – Acid and Metal Carbonate
Balance the following equation for the reaction between hydrochloric acid and calcium carbonate.
$$HCl(aq) + CaCO_3(s) \rightarrow CaCl_2(aq) + H_2O(l) + CO_2(g)$$