Question

What is the pH of a 0.6 M $HNO_3$ solution?

Answer 1

The pH scale is used to determine the strength of the acidic or alkaline solutions. Acidic solutions mostly have a lower pH than the basic or alkaline solutions. More the amount of ${[H]^ + }$ ion the lower the value on the pH scale.

Complete Step By Step Answer:
The acidity of a solution depends on the concentration of the ${[H]^ + }$ ion. The pH is the most convenient method to measure this as it has a wide range of numbers involved.
The formula for finding the pH is: $pH = - \log [{H^ + }]$
It can also be written as: $[{H^ + }] = {10^{ - pH}}$
It is typically said that the pH scale ranges from 0 to 14. A solution with the pH of 7 is said to be neutral. If the pH is less than 7 it is acidic and if it is more than 7 then it is basic/alkaline. This condition is satisfied at standard laboratory conditions. In other conditions it works differently.
We are given 0.6M Nitric acid. Nitric acid is a strong acid hence, will dissociate completely when dissolved in water. The dissociation can be shown as:
$\mathop {HN{O_3}}\limits_{0.6M} \to \mathop {{H^ + }}\limits_{0.6M} + \mathop {NO_3^ - }\limits_{0.6M}$
Hence after dissociation the concentration of ${H^ + }\& NO_3^ -$ are 0.6M respectively. The pH of the solution is equal to $pH = - \log [{H^ + }]$
Using this formula and substituting the values in the formula we get: $pH = - \log (0.6)$ $pH = - ( - 0.222) = + 0.222$
The pH of 0.6 M Nitric acid is 0.222 which is a highly acidic solution. This is the required answer.

Note:
The pH of any solution can be calculated by the formula: $pH = - \log [{H^ + }]$ . If the concentration of the solution is below or equal to ${10^{ - 7}}M$ we’ll have to consider the hydronium ion concentration of the water also. Hence the concentration of Hydronium ions will be the sum of hydronium ions from Nitric acid and hydronium ions from water.