Question

Can you write the equation for the oxidation and reduction half-reactions for the redox reactions below, and then balance the reaction equations? As2O3+HNO3--> As2O5+NO2+H2O

Answer 1

`As_2O_3+ 4HNO_3 -> As_2O_5+4NO_2+2H_2O`

Explanation:

`As_2O_3+ HNO_3 -> As_2O_5+NO_2+H_2O`

We need to identify first the oxidizing agent and the reducing agent.

The oxidation state of `As` in `As_2O_3` is `+3`
The oxidation state of `As` in `As_2O_5` is `+5`
Therefore, `As` is getting oxidized since its oxidation state has increased.

The oxidation state of `N` in `HNO_3` is `+5`
The oxidation state of `N` in `NO_2` is `+4`
Therefore, `N` is getting reduced since its oxidation state has decreased.

Oxidation: `As_2O_3+ 2H_2O -> As_2O_5+4H^++4e^-`
Reduction: `HNO_3 +H^+ +1e^(-)-> NO_2+H_2O`

In order to cancel the electrons in the overall reaction, we should multiply the reduction half-reaction by `4`.

Oxidation: `As_2O_3+ 2H_2O -> As_2O_5+4H^++cancel(4e^-)`

Reduction: `[HNO_3 +H^+ +cancel(1e^(-))-> NO_2+H_2O]" "xx4`

RedOx: `As_2O_3+ 4HNO_3 -> As_2O_5+4NO_2+2H_2O`