Calcium hydride, CaH2\text{CaH}_2CaH2, is an ionic compound. When molten, it can be electrolysed to yield calcium metal and hydrogen gas.
Which equation represents the reaction occurring at the anode during the electrolysis of molten calcium hydride?
Ca2++2e−→Ca\text{Ca}^{2+} + 2\text{e}^- \rightarrow \text{Ca}Ca2++2e−→Ca
2H++2e−→H22\text{H}^+ + 2\text{e}^- \rightarrow \text{H}_22H++2e−→H2
2H−−2e−→H22\text{H}^- - 2\text{e}^- \rightarrow \text{H}_22H−−2e−→H2
4OH−−4e−→O2+2H2O4\text{OH}^- - 4\text{e}^- \rightarrow \text{O}_2 + 2\text{H}_2\text{O}4OH−−4e−→O2+2H2O