Question

The hydroxyl ion concentration of a solution is $1.0\times {{10}^{-8}}M$ . What is the pH of the solution?

Answer 1

Hint: pH means negative logarithm of the hydrogen ion concentration and it can be represented in the form of formula as follows.
$pH=-\log [{{H}^{+}}]$
and the relation between pH and pOH is as follows.
pH + pOH = 14

Complete step by step answer:
- In the question it is given that the hydroxyl ion concentration of the solution is $1.0\times {{10}^{-8}}M$ .
- That means $[O{{H}^{-}}]=1.0\times {{10}^{-8}}M$
- Now we have to find the pH of the solution.
- We can find the pOH by using the concentration of the hydroxyl ion in the solution.
- The pOH of the given solution is
\[\begin{align}
  & pOH=-\log [O{{H}^{-}}] \\
 & pOH=-\log [1.0\times {{10}^{-8}}M] \\
 & pOH=-\log 1-\log {{10}^{-8}} \\
 & pOH=-0-(-8)\log 10 \\
 & pOH=8 \\
\end{align}\]
- From the above calculations we can say that pOh of the given solution is 8.
- But we have to find the pH of the solution.
- To get pH of the solution we have to substitute the pOH of the solution in the equation below.
$pH + pOH = 14$
$pH + 8 =14$
p$H = 14 – 8$
$pH = 6.$
Therefore the pH of the solution having hydroxyl ion concentration of $1.0\times {{10}^{-8}}M$ is 6.

Note: pH means power of hydrogen means the concentration of the hydrogen ion present in the given solution. By using pH value we can say whether the solution is acidic or basic. If pH of the solution is less than 7 then the solution is called acidic and if pH of the solution is greater than 7 then that solution is called basic solution.