Question

Balance the following equation stepwise.
$\mathrm{NaOH}\left(\mathrm{aq}\right)+H_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+H_{2}O\left(l\right)$

Answer 1

Step I: Tabulate the number of atoms of each element present on the reactants and the products side.

Element	Reactant-side	Product-side
N	1	2
O	5	5
H	3	2
S	1	1

[1 mark]

Step II: Start balancing an equation with the compound which contains the maximum number of atoms. Consider the element in this compound, which has an unequal number of atoms on the two sides.

Number of Na atoms	Reactant side (NaOH)	Product side (${\mathrm{Na}}_2{\mathrm{SO}}_4$)
Initially	1	2
To balance	1 $\times$ 2	2

Equation 1: $2\mathrm{NaOH}+H_2{\mathrm{SO}}_4\to {\mathrm{Na}}_2{\mathrm{SO}}_4+H_{2}O$
[1 mark]

Step III: Check whether the equation 1 is balanced or not.

Element	Reactant-side	Product-side
N	2	2
O	6	5
H	4	2
S	1	1

The equation is still not balanced.
[1 mark]

Step IV: Multiply a factor of 2 to the product $H_{2}O$ to balance the equation 1.

Element	Reactant-side	Product-side
N	2	2
O	6	6
H	4	4
S	1	1

The equation is now balanced.
[1 mark]

Step V:

Step V: Write down the final balanced equation along with the physical states.
$2\mathrm{NaOH}\left(\mathrm{aq}\right)+H_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+2H_{2}O\left(l\right)$
[1 mark]