# Decomposition of AsH3

In German problems olympiad 2014, the solution says that decomposition of arsine is not a redox reaction. Why would that be? Shouldn't H turn from -1 to 0 and As from 3+ to 0?

$$\ce{2AsH3 -> 2As + 3H2}$$

• If they really said so, they probably implied that with electronegativity difference that small we may just as well consider both oxidation states 0 from the start, because they are arbitrary anyway. – Ivan Neretin Oct 5 '17 at 17:16