Question

The aqueous solution of $N{a_2}S{O_4}$ will have pH :
a.) equals to 7
b.) less than 7
c.) greater than 7
d.) zero

Answer 1

Hint: We know that a strong acid reacts with a strong base to form salt which is neutral and water. The sodium sulphate is a salt formed by the reaction of sulphuric acid with sodium hydroxide. So, it will have a pH equal to that of a neutral solution.

Complete answer:
The aqueous solution is formed when a solid is dissolved in water. The water aqua is used for water. So, we have to see whether the aqueous solution of sodium sulphate is acidic, basic or neutral.
First, let us see how this aqueous solution of sodium sulphate is formed.
The sulphuric acid reacts with sodium hydroxide to give sodium sulphate. The reaction can be written as -
${H_2}S{O_4} + NaOH \to N{a_2}S{O_4} + {H_2}O$
We know that sulphuric acid is a strong acid and sodium hydroxide is also a very strong base. Further, we also know that a strong acid reacts with a strong base to form salt which is neutral and water.
So, the sulphuric acid will react with sodium hydroxide to form salt sodium sulphate and water. The sodium sulphate is thus neutral in nature.
So, it will have a pH value equal to 7.

So, the option a.) is the correct answer.

Note: It must be noted that the pH of a solution is defined as the negative logarithm of hydrogen ion concentration. The acidic solutions have a pH value less than 7 while the basic solutions have a pH value greater than 7. The neutral solutions have a pH value equal to 7.