Question

In the reaction $2NaOH + {H_2}S{O_4} \to 2{H_2}O + N{a_2}S{O_4}$, how many grams of sodium sulfate will be formed if you start with 200.0 grams of sodium hydroxide and you have excess of sulphuric acid?

Answer 1

To determine the mass of sodium sulfate first find out the mole ratio. In this question two mole of sodium hydroxide form one mole of sodium sulfate. The moles can be calculated by dividing the mass by the molecular weight.

Complete step by step answer:
It is given in the question that 200.0 grams of sodium hydroxide reacts with excess of sulphuric acid.
The given reaction is shown below.
$2NaOH + {H_2}S{O_4} \to 2{H_2}O + N{a_2}S{O_4}$
In this reaction, two mole of sodium hydroxide react with one mole of sulphuric acid to give two mole of water and one mole of sodium sulfate.
To determine the mass of sodium sulfate, first calculate the moles of sodium hydroxide as the value of mass is provided.
The molecular weight of NaOH is 40 g/mol.
The formula is shown below.
$n = \dfrac{m}{M}$
Where,
n is the number of moles
m is the mass
M is the molecular weight
To calculate the number of moles, substitute the values in the above equation.
$\Rightarrow n = \dfrac{{200.0}}{{40g/mol}}$
$\Rightarrow n = 5$
In the equation it is given that 2 mole of sodium hydroxide gives 1 mole of sodium sulphate.
So, to determine the actual mole of sodium sulfate divide the calculated moles of NaOH by 2.
$\Rightarrow \dfrac{5}{2}$
$\Rightarrow 2.5$mol
So 2.5 mol sodium sulfate is formed from 5 mol NaOH.
The molecular weight of sodium sulfate is 142.1 g/mol.
To calculate the mass of sodium sulfate, substitute the values in the formula.
$\Rightarrow 2.5 = \dfrac{m}{{142.1g/mol}}$
$\Rightarrow m = 2.5 \times 142.1$
$\Rightarrow m = 355.25$
Therefore, the mass of sodium sulfate formed when we start with 200.0 grams of sodium hydroxide and you have excess sulphuric acid is 355.25g.

Note:
In this question sulphuric acid is the excess reagent and the sodium hydroxide is the limiting reagent. The excess reagent are those reagents which are fully consumed in the reaction and the limiting reagent are those reagents which fully get consumed during the chemical reaction.