Question

Define pH. Find the pH of 0.05M $Ba{{(OH)}_{2}}$aqueous solution.

Answer 1

We can identify whether a compound is acidic, basic or neutral. The extent of how acidic or basic is the compound can also be calculated. pH of a solution is given by the equation $pH=-{{\log }_{10}}[{{H}^{+}}]$ where, $[{{H}^{+}}]$ is the concentration of the hydrogen ions in the solution.

Complete step by step answer:
pH of a solution is a measure of the concentration of hydrogen ions present in a solution. It gives the measure of acidity or basicity of the solution. pH can also be defined as the negative logarithm to the base 10 of molar concentration of hydrogen ion in the solution. Lower the pH values, the more acidic the solution is and if the values are high, the solution is basic. For bases usually pOH is calculated. It is the negative logarithm to the base of the molar concentration of $O{{H}^{-}}$ ions present in the solution.
$pH=-{{\log }_{10}}[{{H}^{+}}]$
It is given that the concentration of is $Ba{{(OH)}_{2}}$0.05M.
$[Ba{{(OH)}_{2}}]=0.05M$
When $Ba{{(OH)}_{2}}$ ionises in water, it processes 2 $O{{H}^{-}}$ ions.
So, $[O{{H}^{-}}]=2\times [Ba{{(OH)}_{2}}]=2\times 0.05M$=0.10M
$pOH=-{{\log }_{10}}[O{{H}^{-}}]$
$pOH=-{{\log }_{10}}0.10=1$
We know that $pOH+pH=14$
$pH=14-pOH=14-1=13$
Hence, the pH of is $Ba{{(OH)}_{2}}$13. It is basic.

Additional Information:
For a neutral solution, the pH value will be 7. All the solutions with the value less than 7 are acidic and greater than 7 are basic. The neutral value depends on temperature. Some strong acid solutions can have pH value less than 0 and some strong basic solutions can have ph value greater than 14 too.

Note:
While calculating pH of a base, the concentration of $O{{H}^{-}}$ ions are taken and its concentration’s negative logarithm to the base is taken, that is, we get the pOH only. We have to then find pH by using the equation $pOH+pH=14$.