Question

HCl is a strong acid that dissociates in water:

\(HCl \to {H^ + } + C{l^ - }\). What is the pH of 0.01M HCl?

Short answer

The pH acts as a scale to find out the property of the solution as acidic or basic.The pH of 0.01M HCl is 2.

Step-by-step solution

Dissociation of HCl in aqueous solution

The dissociation of HCl is represented as follows.

\(HCl \to {H^ + } + C{l^ - }\)

\(pH = \log ({10^{ - 2}})\)\(H \to {H^ + } + {e^ - }\)

\(Cl + {e^ - } \to C{l^ - }\)

As per the above dissociation reaction, one mole of hydrogen ion reacts with one mole of chloride ion.

From the given question, the 0.01M hydrogen ions react with 0.01M chloride ion.

Description of pH

The pH is defined as the negative logarithm of hydrogen ions. The formula for pH is represented as follows.

\(pH = - \log \left( {{H^ + }} \right)\)

Calculation for 0.01M HCl

\(pH = - \log \left( {0.01} \right)\)

\(pH = - \log \left( {{{10}^{ - 2}}} \right)\)

\(pH = 2\log \left( {10} \right)\)

(Whereas log 10=1)

\(pH = 2\)

Hence, the pH of 0.01M solution of hydrogen chloride is 2.