Question

In a sulphuric acid (h2so4) - sodium hydroxide (naoh) acid-base titration, 17.3 ml of 0.126 m naoh is needed to neutralize 25 ml of h2so4 of unknown concentration. find the morality of the h2so4 solution, given that the neutralization reaction that occurs is:

Answer 1

The balanced equation for the neutralisation reaction is as follows
2NaOH + H₂SO₄ ---> Na₂SO₄ + 2H₂O
stoichiometry of NaOH to H₂SO₄ is 2:1
the number of moles of NaOH reacted  - 0.126 mol/L  x 0.0173 L = 0.00218 mol
if 2 mol of NaOH reacts with 1 mol of H₂SO₄ 
then 0.00218 mol of NaOH reacts with - 0.00218 / 2 = 0.00109 mol of H₂SO₄ 
molarity is the number of moles of solute in 1 L solution
therefore if 25 mL contains - 0.00109 mol 
then 1000 mL contains - 0.00109 mol / 25 mL  x 1000 mL = 0.0436 mol/L
therefore molarity of H₂SO₄ is 0.0436 M