Practice Balancing Equations in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

The process of adjusting the coefficients (the numbers placed before chemical formulas) in a chemical equation so that the number of atoms of each element.

Atoms can't appear or disappear β€” every atom on the left must show up on the right.

Showing a random 20 of 50 problems.

Example 1

medium
Balance: C3H8+O2β†’CO2+H2O\text{C}_3\text{H}_8 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}.

Example 2

medium
Why does changing H2OH_2O to H2O2H_2O_2 to balance oxygen break the rule?

Example 3

medium
Balance: Al+HCl→AlCl3+H2Al + HCl \rightarrow AlCl_3 + H_2.

Example 4

medium
Balance: Al+O2β†’Al2O3\text{Al} + \text{O}_2 \rightarrow \text{Al}_2\text{O}_3.

Example 5

easy
To balance an equation you adjust which numbers?

Example 6

hard
Balance: Al+Fe2O3β†’Al2O3+Fe\text{Al} + \text{Fe}_2\text{O}_3 \rightarrow \text{Al}_2\text{O}_3 + \text{Fe} (thermite).

Example 7

easy
Balance the equation: Fe+O2β†’Fe2O3\text{Fe} + \text{O}_2 \rightarrow \text{Fe}_2\text{O}_3.

Example 8

medium
Balance: Fe+O2β†’Fe2O3Fe + O_2 \rightarrow Fe_2O_3.

Example 9

hard
Balance: Fe2(SO4)3+NaOH→Fe(OH)3+Na2SO4\text{Fe}_2(\text{SO}_4)_3 + \text{NaOH} \rightarrow \text{Fe(OH)}_3 + \text{Na}_2\text{SO}_4.

Example 10

easy
In the balanced equation 2H2+O2β†’2H2O2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}, how many H atoms appear on each side?

Example 11

hard
Balance: H2S+O2β†’SO2+H2O\text{H}_2\text{S} + \text{O}_2 \rightarrow \text{SO}_2 + \text{H}_2\text{O}.

Example 12

hard
Balance: Ca(OH)2+H3PO4β†’Ca3(PO4)2+H2O\text{Ca(OH)}_2 + \text{H}_3\text{PO}_4 \rightarrow \text{Ca}_3(\text{PO}_4)_2 + \text{H}_2\text{O}.

Example 13

medium
Balance: NH3+O2β†’NO+H2O\text{NH}_3 + \text{O}_2 \rightarrow \text{NO} + \text{H}_2\text{O}.

Example 14

medium
Balance: Al+HCl→AlCl3+H2\text{Al} + \text{HCl} \rightarrow \text{AlCl}_3 + \text{H}_2.

Example 15

hard
Balance: Ag2O→Ag+O2\text{Ag}_2\text{O} \rightarrow \text{Ag} + \text{O}_2.

Example 16

medium
Balance: CH4+O2β†’CO2+H2O\text{CH}_4 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}.

Example 17

medium
Balance the equation for the formation of ammonia: N2+H2β†’NH3\text{N}_2 + \text{H}_2 \rightarrow \text{NH}_3.

Example 18

medium
Balance: Fe+Cl2β†’FeCl3\text{Fe} + \text{Cl}_2 \rightarrow \text{FeCl}_3.

Example 19

medium
Balance: P4+O2β†’P4O10P_4 + O_2 \rightarrow P_4O_{10}.

Example 20

medium
Balance: Mg+HCl→MgCl2+H2\text{Mg} + \text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2.