Question

Addition of water to $X$ solution will not change concentration of $H_3{O}^{+}$. $X$ is:

• A. chemical pH indicator
• B. acid/base buffer
• C. anhydrous solution
• D. hypotonic solution
• E. supersaturated solution

Answer 1

The correct option is B acid/base buffer

Addition of water to $X$ solution does not change the $pH$ of the solution, which means the concentration of the species present changes in such a way that the $pH$ remains the same. This is possible for acid/base buffer.

$pH=p{k}_a+\log \frac{\left[salt\right]}{\left[acid\right]}$

Since the volume changes the same for both salt and acid, the ratio $\frac{\left[salt\right]}{\left[acid\right]}$ remains the same and hence $pH$ also remains the same. Same in the case of basic buffer solution.