Chemical and Ionic Equilibrium 2 Question 20
20. The $\mathrm{pH}$ of $0.1 \mathrm{M}$ solution of the following salts increases in the order
$(1999,2 \mathrm{M})$
(a) $\mathrm{NaCl}<\mathrm{NH}_{4} \mathrm{Cl}<\mathrm{NaCN}<\mathrm{HCl}$
(b) $\mathrm{HCl}<\mathrm{NH}_{4} \mathrm{Cl}<\mathrm{NaCl}<\mathrm{NaCN}$
(c) $\mathrm{NaCN}<\mathrm{NH}_{4} \mathrm{Cl}<\mathrm{NaCl}<\mathrm{HCl}$
(d) $\mathrm{HCl}<\mathrm{NaCl}<\mathrm{NaCN}<\mathrm{NH}_{4} \mathrm{Cl}$
Chemical and Ionic Equilibrium
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Solution:
- $\mathrm{NaCN}$ is basic salt, has highest $\mathrm{pH}$ while $\mathrm{HCl}$ has lowest $\mathrm{pH}$. $\mathrm{NaCl}$ is neutral salt has $\mathrm{pH}=7$ while $\mathrm{NH}_{4} \mathrm{Cl}$ is acidic salt, has $\mathrm{pH}$ less than 7.
$$ \mathrm{pH}: \quad \mathrm{HCl}<\mathrm{NH}_{4} \mathrm{Cl}<\mathrm{NaCl}<\mathrm{NaCN} $$
