Question

A 150 mL sample of hydrochloric acid (HCl) completely reacted with 60.0 mL of a 0.100 M NaOH solution. The equation for the reaction is given below.

HCl + NaOH Right arrow. NaCl + H2O

What was the original concentration of the HCl solution?
0.040 M
0.25 M
1.50 M
2.50 M

Answer 1

Moles NaOH = 0.0600 L × 0.100 M = 0.00600 mol.
Reaction is 1:1, so moles HCl = 0.00600 mol.
[HCl] = 0.00600 mol / 0.150 L = 0.0400 M.

Answer: 0.040 M.