Question

It is found that $0.1M$ solution of three sodium salts $NaX$, $NaY$ and $NaZ$ have $pH$ $7.0,9.0$ and $11.0$ respectively. Arrange the acids ($HX,HY$ and $HZ$) in order of increasing acidic character.

• A. $HY>HX>HZ$
• B. $HX>HY>HZ$
• C. $HX>HZ>HY$
• D. $HZ>HY>HX$

Answer 1

The correct option is B $HX>HY>HZ$

It is found that $0.1M$ solution of three sodium salts $NaX$, $NaY$ and $NaZ$ have $pH$ $-7.0,9.0$ and $11.0$ respectively.

The acids ($HX,HY$ and $HZ$) in order of decreasing acidic character is $HX>HY>HZ$. The pH of $NaX$ is lowest. Hence, the solution of $NaX$ will have maximum hydrogen ion concentration. Hence, $HX$ is the strongest acid.

Similarly, the pH of $NaZ$ is maximum. The solution of $NaZ$ will have the lowest hydrogen ion concentration. Hence $HZ$ is the weakest acid.