A solution of hydrochloric acid of unknown concentration was titrated with 0.10 M NaOH. If a 100.-mL sample of the HCl solution required exactly 1.0 mL of the NaOH solution to reach the equivalence point, what was the initial pH of the HCl solution

The initial pH of the HCl solution is 3

Explanation:

To calculate the concentration of acid, we use the equation given by neutralization reaction:

where,

are the n-factor, molarity and volume of acid which is HCl

are the n-factor, molarity and volume of base which is NaOH.

We are given:

Putting values in above equation, we get:

1 mole of HCl produces 1 mole of ions and 1 mole of ions

To calculate the pH of the solution, we use the equation:

We are given:

Putting values in above equation, we get:

Hence, the initial pH of the HCl solution is 3