What is the concentration of the H2SO4 solution?

Question

25.00 mL of H₂SO₄ solution with an unknown concentration was titrated to a phenolphthalein endpoint with 47.73 mL of a 0.1459 M NaOH solution.

What is the concentration of the H₂SO₄ solution?

Answer 1

H2SO4 + 2NaOH ==> Na2SO4 + 2H2O .. balanced equation

moles NaOH needed = 47.73 ml x 1 L / 1000 ml x 0.1459 mol / L = 6.964x10^-3 mols NaOH

moles H2SO4 present = 6.964x10^-3 mols NaOH x 1 mol H2SO4 / 2 mol NaOH = 3.482x10^-3 mols

concentration of H2SO4 = 3.482x10^-3 mols / 25.00 mls x 1000 ml / L = 0.1393 M