# How to convert a sulfate into a sulfide?

## My texbook contains a scheme of interactions of suflur and its compounds. The box titled "sulfates" is connected by an arrow to the box titled "sulfide". Please provide an example reaction. Let's say we have the sulfate CuSO4. Is there a way to turn it into CuS in a single reaction?

$S {O}_{4}^{2 -} + 8 {H}^{+} + 4 {e}^{-} \rightarrow {S}^{2 -} + 4 {H}_{2} O \left(l\right)$
I believe there are certain circumstances in which this reduction reaction can be performed enzymatically. The problem is you have to reduce the sulfate in the presence of $C {u}^{2 +}$, which has a much lower reduction potential.