Question

The concentration of hydrogen ions in a sample of soft drink is $3.8 \times {10^{ - 3{\text{ }}}}{\text{M}}$ . What is its ${\text{pH}}$ ?

Answer 1

pH is defined as the negative logarithm of hydrogen ion concentration, that is, ${\text{pH}} = - \log \left[ {{{\text{H}}^ + }} \right]$. Substituting the value concentration of hydrogen ion gives us the value of pH.

Complete step by step solution:
The pH scale lies in between 0 to 14 at the standard temperature and pressure. If the pH is less than 7 then the solution is acidic. If the pH is equal to 7 then the pH is neutral and if the pH is greater than 7 then the solution is basic in nature. pH is temperature dependent and change in temperature of the surrounding change the pH range. The concentration of hydrogen ion is given to us and so putting the concentration in formula we will get:
\Rightarrow$$${\text{pH}} = - \log \left[ {3.8 \times {{10}^{ - 3{\text{ }}}}{\text{M}}} \right]$$ Taking logarithm of concentration we will get: \Rightarrow$$${\text{pH}} = 2.42$$
**The pH comes out to be less than 7 and hence the solution is acidic or the sample of soft drink is acidic in nature.
**
Note:
The pH stands for power of hydrogen. The pH is defined for the solution to determine whether the solution is acidic, basic or neutral. The level of hydrogen ion concentration and the level of hydroxide ion concentration in a solution determine the behaviour of solution. If the concentration of hydrogen ions is more than the concentration of hydroxide then the solution is acidic in nature. If the concentration of hydroxide ion is more than the concentration of hydrogen ion then the solution is basic in nature. If the concentration of hydrogen ions becomes equal to concentration of hydroxide ions in the solution then the solution is neutral in nature.