How to balance a chemical equation

to balance a chemical equation the amount of reactants must be equal to the amount of products, an easy way to balance it is write out how many you have on both sides

Explanation:

if you're dealing with molecular equations you would do it like this:

eg. A double displacement reaction between magnesium hydroxide and hydrochloric acid

Mg(OH)2 (aq) + HCl (aq) = MgCl2 (aq) + H2O (l)

Mg-1. Mg-1

O-2. O-1 *2

H-2. H-2

Cl-1 *2 Cl-2

Balanced eq: Mg(OH)2 (aq) + 2HCl (aq) = MgCl2 (aq) + 2H2O (l)

if you're dealing with ionic equations , you would deal with charges and you would need to cancel out spectator ions, like this:

Mg^2+(aq) + 2OH^-(aq) + 2H^+ (aq) + 2Cl^- (aq) = Mg ^2+(aq)+ 2Cl^- (aq) + H20 (l)

the spectator ions are the ones that are the same on both sides which would be the Mg^2+ and the 2Cl^- so when writing the net ionic equation, it would just be:

2OH^-(aq) + 2H^+ (aq) = + H20 (l)