Question

Consider 0.10 M solutions of the following compounds: ${\mathbf{AlCl}}_3,\mathbf{NaCN},\mathbf{KOH},{\mathbf{CsClO}}_4,\mathbf{and}\mathbf{NaF}$. Place these solutions in order of increasing pH.

Short answer

The increasing order of pH :${\mathrm{AlCl}}_3<{\mathrm{CsClO}}_4<\mathrm{NaF}<\mathrm{NaCN}<\mathrm{KOH}$

Step-by-step solution

Nature of AlCl3 solution

As ${\mathrm{AlCl}}_3$is a salt of a strong acid (HCl) and weak base $\mathrm{Al}{\left(\mathrm{OH}\right)}_3$ , the pH of the solution should be less than 7, and the solution would be acidic.

Nature of NaCN Solution

As NaCN is a salt of a weak acid (HCN) and strong base NaOH, the solution would be basic, and the pH would be more than 7.

KOH Solution

As KOH is a strong base, the solution [OH^-] =0.1 and pH =13.

Nature of CsClO4 Solution

As CsClO₄is a salt of a strong acid (HClO₄) and strong base CsOH, the solution would be neutral with pH=7.

Nature of NaF Solution

As NaF is a salt of a weak acid (HF) and strong base NaOH, the solution would be basic, and the pH would be more than 7.

But NaCN is more basic than NaF as CN^- is more basic than F^-.

The order of pH:

${\mathrm{AlCl}}_3<{\mathrm{CsClO}}_4<\mathrm{NaF}<\mathrm{NaCN}<\mathrm{KOH}$