Question

A mixture of the sulphides of $A{s}_2{S}_3,S{b}_2{S}_3$ and $B{i}_2{S}_3$ was treated with a $N{a}_{2}S$ solution. Which sulphide remained undissolved? Write the equation of the sulphide dissolving reactions.

• A. $A{s}_2{S}_3$
• B. $S{b}_2{S}_3$
• C. $B{i}_2{S}_3$
• D. $B{i}_2{S}_3$ & $S{b}_2{S}_3$

Answer 1

The correct option is C $B{i}_2{S}_3$

$B{i}_2{S}_3$ remains undissolved while
$A{s}_2{S}_3+3N{a}_{2}S⟶\underset{soluble}{2N{a}_3\left[As{S}_3\right]}$
$S{b}_2{S}_3+3N{a}_{2}S⟶\underset{soluble}{2N{a}_3\left[Sb{S}_3\right]}$