Data

Volume Na₂SO₄ = 20cm³ (0.02dm³)
Molanty of Na₂SO₄ =0.4M

Asked
Mass of Na₂CO₃
Equation for the reaction
Na₂CO₃ + Na₂SO₄ → Na₂SO₄ + H₂O + CO₂

To find mole of Na₂SO₄
Mole = molanty x volume in dm³
= 0.4m × 0.02dm³
= 0.008 mole

To use mole equivalent between Na₂SO₄ and Na₂CO₃
1 mole Na₂CO₃ Ξ 1mole Na₂SO₄
?? Na₂CO₃ Ξ 0.008 mole Na₂SO₄

= (4 moles × 0.008 mole) / 1mole
= 0.008 mole of Na₂CO₃
Mass = 0.008 × 106
= 0.848g

0.848g of sodium carbonate was used in the reaction.