Molarity Formula

Question

In a titration experiment, 45.7 mL of 0.500 M HCl is used to neutralize 20.0 mL of a NaOH solution. What is the molarity of the NaOH solution?

A) 0.571 M

B) 0.600 M

C) 1.14 M

Answer 1

The balanced chemical equation for the reaction between HCl and NaOH is:

HCl + NaOH → NaCl + H2O

From the balanced equation, we can see that one mole of HCl reacts with one mole of NaOH. Therefore, the number of moles of HCl used in the reaction is:

moles HCl = Molarity of HCl × Volume of HCl used in the reaction = 0.500 M × 0.0457 L = 0.02285 moles HCl

Since the reaction is a neutralization reaction, the number of moles of NaOH used in the reaction is equal to the number of moles of HCl used in the reaction. Therefore:

moles NaOH = moles HCl = 0.02285 moles NaOH

The molarity of the NaOH solution can be calculated using the following equation:

Molarity of NaOH = moles NaOH ÷ Volume of NaOH used in the reaction

We are given that the volume of NaOH used in the reaction is 20.0 mL, or 0.0200 L. Therefore:

Molarity of NaOH = 0.02285 moles NaOH ÷ 0.0200 L = 1.14 M

Therefore, the molarity of the NaOH solution is C) 1.14 M.