A 25 cm3 sample of an unknown concentration of sulfuric acid was titrated against 0.1 mol dm-3 sodium hydroxide. The average titre was 20 cm3. Calculate the concentration of the sulfuric acid.

Balanced equation: H₂SO₄ + 2NaOH → 2H₂O + Na₂SO₄moles of NaOH = c x v = 0.1 mol dm^-3 x (20/1000) dm³ = 0.002 molStoichiometry: H₂SO₄:NaOH = 1:2moles of H₂SO₄ = (0.002 mol)/2 = 0.001 molc=n/v= (0.001 mol)/((25/1000) dm³)= 0.04 mol dm^-3