Calculate the mass of the formed salt if 240 g of sodium hydroxide was taken in the reaction with sulfuric acid.

Given:

m (NaOH) = 240 g

To find:

m (salt) -?

Solution:

2NaOH + H2SO4 = Na2SO4 + 2H2O, – we solve the problem based on the composed reaction equation:

1) Find the amount of sodium hydroxide that has reacted:

n (NaOH) = m: M = 240 g: 40 g / mol = 6 mol.

2) We compose a logical expression:

if 1 mol Na2SO4 requires 2 mol NaOH,

then x mol Na2SO4 will require 6 mol NaOH,

then x = 3 mol.

3) Find the mass of sodium sulfate formed as a result of the reaction:

m (Na2SO4) = n * M = 3 mol * 142 g / mol = 426 g.

Answer: m (Na2SO4) = 426 g.