Question

Calculate the pH of 0.1M HCl.

Answer 1

The given compound hydrochloric acid is a strong acid. The strong acid has a characteristic that dissolves in water; it completely dissolves and dissociates to give hydronium ion.

Complete step by step answer:
pH is defined as the quantitative measure for the nature of aqueous solution whether it is acidic or basic. A solution whose pH value is less than 7 than it is said to be acidic. A solution whose pH value is more than 7 than it is said to be basic. The solution whose pH value is 7 then it is said to be neutral.
A strong acid is considered as a strong electrolyte that fully gets dissolved in water and breaks to give hydrogen ion or hydronium ion.
The dissociation of hydrochloric acid in water is shown below.
$HCl + {H_2}O \to {H_3}{O^ + } + C{l^ - }$
Given, the concentration of hydrochloric acid is 0.1 M.
M is the molarity, which is defined as the amount of solute dissolved in one liter of solution.
As hydrochloric acid fully dissolves in water, therefore 0.1 M HCl dissociate to give 0.1 M ${H^ + }$ion and 0.1 M $C{l^ - }$ ion.
The pH of the solution is the negative logarithm of hydrogen ion or hydronium ion concentration.
The formula used to calculate the pH of the solution is shown below.
$pH = - \log [{H_3}{O^ + }]$
Substitute the value of the concentration of hydronium ion in the above equation.
$pH = - \log [0.1]$
$\Rightarrow pH = 1$
Thus, the pH of 0.1 M HCl is 1.

Note:
Hydronium ion and hydrogen ion are the same. The hydronium ion concentration can be obtained from the pH by a reverse expression.
$[{H_3}{O^ + }] = anti\log ( - pH)$