How many milliliters of a 0.40 m solution of hydrochloric acid are necessary to neutralize 25 ml of a 0.20 m sodium hydroxide solution?

12.5 mL of HCl

Explanation:

The balanced chemical equation for the neutralization reaction is as follows

NaOH + HCl —> NaCl + H2O

Molar ratio of NaOH to HCl is 1:1

For neutralization to happen the number of NaOH moles is equal to the number of HCl moles

Number of NaOH moles reacted - 0.20 mol/L x 0.025 L = 0.005 mol

Therefore number of HCl moles reacted - 0.005 mol

Concentration of HCl is 0.40 mol/L

Concentration = number of moles / volume

Rearranging the equation

Volume = number of moles / concentration

Volume = 0.005 mol / 0.40 mol/L

= 0.0125 L

Volume of HCl added is 12.5 mL