# What kind of reaction occurs when you mix aqueous solutions of barium sulfide and sulfuric acid?

$B a S \left(a q\right) + {H}_{2} S {O}_{4} \left(a q\right) \rightarrow B a S {O}_{4} \left(s\right) \downarrow + {H}_{2} S \left(a q\right)$
This is (i) an acid base reaction, and (ii) a precipitation reaction as barium sulfate is pretty insoluble stuff (${K}_{s p} = 1.08 \times {10}^{-} 9$ at $298 \cdot K$).