Question

When the pH of a solution is $12.83$, what is $[{H^ + }]$?

Answer 1

Hint: The pH is defined as the negative logarithm of hydrogen ion concentration in the solution. This describes the acidity and basicity of the solution. The pH scale contains values from one to fourteen, one being most acidic and fourteen being most basic. The pH value is determined using pH paper, pH meter, etc. The pH value is calculated using the hydrogen ion concentration, if pH is known, the concentration of hydrogen ion can be calculated.

Complete answer:
The pH can be calculated using the formula - $pH = - \log [{H^ + }]$
Now rearranging the same formula we can calculate the $[{H^ + }]$ , i.e. $[{H^ + }] = {10^{ - pH}}$ , where,
$[{H^ + }]$ - hydrogen ion concentration in solution
${10^{ - pH}}$ - ten is the base of power and power being negative of the pH.
Now, putting the given value of pH, we have,
Concentration of hydrogen ion $[{H^ + }] = {10^{ - 12.83}}$
Now solving the equation, we have $ [{H^ + }] = 1.479108388 \times {10^{ - 13}}$
Rounding off the calculated value, we have $ [{H^ + }] = 1.479 \times {10^{ - 13}}$
Thus, the solution of pH $12.83$ will have the concentration of hydrogen ion as $ 1.479 \times {10^{ - 13}}$ and the unit will be mol per litre.
Hence the answer will be - $ 1.479 \times {10^{ - 13}} \cdot mol \cdot {L^{ - 1}}$

Note:
The given solution has pH more than 7, so the solution will be basic in nature. This simply means that the hydrogen ion concentration is very low in this solution, i.e. of range $ {10^{ - 13}}$ . The pOH value can also be calculated using formula $pH + pOH = 14$ . So, the pOH value will be $1.17$ . The pOH value defines the basicity of solution.