To determine the concentration of a solution of chlorous acid, a 50.00-mL sample is placed in a flask and titrated with a 0.1382 M solution of sodium hydroxide. A volume of 26.37 mL is required to reach the phenolphthalein endpoint. Calculate the concentration of chlorous acid in the original sample.

The answer to your question is Molarity = 0.073

Explanation:

Data

Chlorous acid = HClO₂

Volume = 50 ml

[HClO₂] = ?

Sodium hydroxide = NaOH

[NaOH] = 0.1382 M

Volume = 26.37 ml

Process

1.- Write the balanced chemical reaction

                   HClO₂  +  NaOH  ⇒   H₂O + NaClO₂

2.- Calculate the moles of NaOH

Molarity = moles / volume

Moles = Molarity x volume

Moles = 0.1382 x 0.02637

Moles = 0.00364

3.- Calculate the moles of HClO₂

                 1 mol of HClO₂ 1 mol of NaOH

                 x                         0.00364 moles

                 x = (0.00364 x 1) / 1

                 x = 0.00364 moles of HClO₂

4.- Calculate the concentration of HClO₂

Molarity = 0.00364 / 0.05

Molarity = 0.073