A 25.00 mL sample of 0.2500 M sulfuric acid is titrated with 0.5000 M sodium hydroxide solution. What volume of sodium hydroxide solution is required?

Answer 1

H2SO4 is a diprotic acid, in other words, to fully neutralize is requires twice as much base. NaOH is a strong base, but two NaOH are required for each H2SO4 to fully neutralize the acid.

A .5000 M solution of sodium hydroxide has exactly twice as many molecules of NaOH as a .25 M solution of sulfuric acid, so the same quantity, 25.00 ml is required.

Formally, you could write:

.2500 mols H2SO4/1000ml x .25 ml = .0625 mols H2SO4 x 2 mols NaOH/1 mol H2SO4 x 1000 ml NaOH/.5000 mols NaOH = .25 ml NaOH

You can verify that all of the units cancel, leaving the answer in the correct units.