To neutralize 1 mol of sulfuric acid, 2 mol of sodium hydroxide are required. How many liters of 1 M NaOH are needed to exactly neutralize 1 L of 1 M H2SO4?

• A. 1
• B. 2
• C. 0.5
• D. 4

Answer: (B)

Neutralization hinges on stoichiometry and the relation between moles and solution concentration. Sulfuric acid is diprotic, so each mole can release 2 protons and thus requires 2 moles of base to neutralize. A liter of 1 M H2SO4 contains 1 mole of acid, so it needs 2 moles of NaOH to neutralize it. A 1 M NaOH solution delivers 1 mole of NaOH per liter, so to obtain 2 moles you need 2 liters. Therefore, 2 liters of 1 M NaOH are required to exactly neutralize 1 liter of 1 M H2SO4.