Question

When equal volumes of the following solutions are mixed precipitation of $AgCl (K_{sp} = 1.8 x \times 10^{ - 1 0 }) $ will occur only with

• A. $ 10^{ - 4 } \, M \, ( Ag^+ )$ and $10^{ - 4 } \, M \, ( Cl^- )$
• B. $ 10^{ - 5 } \, M \, ( Ag^+ ) $ and $ 10^{ - 5 } \, M \, ( Cl^- )$
• C. $ 10^{ - 6 } \, M \, ( Ag^+ )$ and $10^{ - 6 } \, M \, ( Cl^- )$
• D. $ 10^{ - 10 } \, M \, ( Ag^+ )$ and $10^{ - 10 } \, M \, ( Cl^- )$

Answer 1

Answer: (A)

For precipitation to occur, $K_{ s p } < Q_{ sp} $,
$ Q_{ sp } = \bigg( \frac{ 10^{ - 4 }}{ 2 } \bigg) \, \bigg( \frac{ 10^{ - 4 }}{ 2 } \bigg) = 2.5 \times 10^{ - 9 } > \, K_{ sp} $
Hence, precipitate will be formed in this case.
In all other case, $Q_{sp} < K_{sp}$ and no precipitation will occur.