Question

What is the concentration of the HCl if its pH is 3?

Answer 1

Hint: The relation between the hydrogen ion concentration and pH of the solution is as follows.
pH = - log [${{H}^{+}}$ ]
Here pH = pH of the solution
[${{H}^{+}}$ ] = Concentration of the hydrogen ion.

Complete answer:
- In the question it is asked to calculate the concentration of the HCl in a solution whose pH is 3.
- By using the following formula we can calculate the concentration of the HCl which is present in the solution whose pH is 3.
pH = - log [${{H}^{+}}$ ]
Here pH = pH of the solution = 3
[${{H}^{+}}$ ] = Concentration of the hydrogen ion.
- Substitute the known or given values in the above formula to get the concentration of the HCl in the solution whose pH is 3.
\[\begin{align}
  & 3=-\log [{{H}^{+}}] \\
 & [{{H}^{+}}]={{10}^{-3}}M \\
 & [{{H}^{+}}]=0.001M \\
\end{align}\]
- Therefore the concentration of the HCl in the solution whose pH – 3 is 0.001 M.
- Means we are going to express the hydrogen ion concentration in the given solution in the terms of molarity.
- The other terms used to express the concentration of the hydrogen ion are normality and molality.

Note:
If the pH of the solution is too less then the solution is highly acidic in nature and if the pH of the solution is too high then the solution is highly basic in nature. Soaps are best examples for basic compounds and citrus fruits are examples for acidic compounds.