Question

The pH of a solution is 8. What will be its hydrogen ion concentration?
(A) ${{10}^{-8}}$
(B) $-{{10}^{-9}}$
(C) ${{2}^{-8}}$
(D) None

Answer 1

Hint: pH is criteria which generally tells whether the given solution or compound is acidic, basic or neutral in nature. The pH of any aqueous solution which contains hydrogen ions can be calculated by
$\text{pH}=-\text{log}\left[ {{\text{H}}^{+}} \right]$
Formula used: $\text{pH}=-\text{log}\left[ {{\text{H}}^{+}} \right]$

Complete step by step solution:
In the given statement the pH of the solution is and we have to calculate the hydrogen ion concentration in the solution.
pH=
By applying the formula
$\text{pH}=-\text{log}\left[ {{\text{H}}^{+}} \right]$
$8=-\text{log}\left[ {{\text{H}}^{+}} \right]\to -8=\text{log}\left[ {{\text{H}}^{-}} \right]$
 Taking antilog10 on both side
$\begin{align}
& \text{Antilo}{{\text{g}}_{10}}\left( -8 \right)=\left[ {{\text{H}}^{+}} \right] \\
& {{10}^{-8}}={{\text{H}}^{+}} \\
\end{align}$
So, the concentration of hydrogen ion$={{10}^{-8}}$

Option ‘A’ is the correct answer.

Additional information: pH is the criteria which tell whether any solution is acidic or basic in nature.
Acids: Acids is defined as the material which is capable of losing hydrogen ions or protons.
$\text{AH}\to {{\text{A}}^{-}}+{{\text{H}}^{+}}$
Bases: bases is defined as the material which is capable of exchanging hydroxyl ions.
$\text{BOH}\to {{\text{B}}^{+}}+\text{O}{{\text{H}}^{-}}$
Some compounds which neither possess the property of an acid nor possess the property of base fall under the category of amphoteric substance. For example water acts as amphoteric.

Note: Knowledge of the calculation of pH of solution and formula used must to solve this kind of problem. If the pH of any solution is less than then it is acidic in nature; if the pH is equal to then it is neutral and if the pH of solution is greater than then it is basic in nature. The H of human blood ranges from $7\cdot 3$ to $7\cdot 5$.