Question

Translate the following statement into chemical equations and balance:

Sodium metal reacts with water to give sodium hydroxide and hydrogen gas.

Answer 1

Sodium metal reacts with water to give sodium hydroxide and hydrogen gas.

1.Reaction

$\mathrm{Na}+\mathrm{H}{}_2\mathrm{O}\to \mathrm{NaOH}+\mathrm{H}{}_2$

(Sodium) (Water) (Sodium hydroxide) (Hydrogen)

2. Balancing steps

Step 1: Write unbalanced equation.

$\mathrm{Na}+\mathrm{H}{}_2\mathrm{O}\to \mathrm{NaOH}+\mathrm{H}{}_2$

Step 2: Write down the number of atoms of each element present on both reactant as well as product side.

Element Reactant side Product side

$\mathrm{H}$ $2$ $3$

$\mathrm{Na}$ $1$ $1$

$\mathrm{O}$ $1$ $1$

Step 3: Add coefficients to balance the number of atoms at both the sides

Firstly write $2$ before $\mathrm{H}{}_2\mathrm{O}$

$\mathrm{Na}+2\mathrm{H}{}_2\mathrm{O}\to \mathrm{NaOH}+\mathrm{H}{}_2$

Secondly add $2$ before $\mathrm{NaOH}$

$\mathrm{Na}+2\mathrm{H}{}_2\mathrm{O}\to 2\mathrm{NaOH}+\mathrm{H}{}_2$

Finally add $2$ before $\mathrm{Na}$

$2\mathrm{Na}+2\mathrm{H}{}_2\mathrm{O}\to 2\mathrm{NaOH}+\mathrm{H}{}_2$

Balanced equation is:

$2\mathrm{Na}\left(\mathrm{s}\right)+2\mathrm{H}{}_2\mathrm{O}\left(\mathrm{l}\right)\to 2\mathrm{NaOH}\left(\mathrm{aq}\right)+\mathrm{H}{}_2(\mathrm{g})$

(Sodium) (Water) (Sodium hydroxide) (Hydrogen)