Question

Assign the oxidation numbers for the following equation.2H2 + O2 → 2H2OWhich reactant is the reducing agent, and which reactant is the oxidizing agent?

Answer 1

In the equation 2H2 + O2 → 2H2O, hydrogen is being oxidized and oxygen is being reduced. Hydrogen is the reducing agent and oxygen is the oxidizing agent.

Step-by-step explanation:

In order to assign oxidation numbers to the atoms in the equation 2H2 + O2 → 2H2O, we need to determine the rules for assigning oxidation numbers.

The oxidation number of hydrogen is +1, while the oxidation number of oxygen is typically -2. However, in this case, oxygen has an oxidation number of 0 since it is in its elemental form.

Given this, we can see that in the reactant H2, each hydrogen atom has an oxidation number of 0. In the product H2O, each hydrogen atom has an oxidation number of +1. Therefore, hydrogen is being oxidized from an oxidation number of 0 to +1.

As for the oxidizing and reducing agents, the reducing agent is the substance that is being oxidized and the oxidizing agent is the substance that is being reduced.

In this case, hydrogen is being oxidized from an oxidation number of 0 to +1, so it is the reducing agent. Oxygen is being reduced from an oxidation number of 0 to -2, so it is the oxidizing agent.

Answer 2

In order to this question, we need to know some terms to solve it.

The reducing agent is the one that loses electrons. It is said to have been oxidized.

The oxidizing agent is the one that gains electrons. It is said to have been reduced.

H2 and O2 on the left side of the reaction both have a 0 as oxidation state.

(Atoms of diatomic molecules like hydrogen, chlorine, oxygen, etc, or of metallic chemical elements like Zn, Cu, Na, etc are assigned zero oxidation numbers)

Let's analyze what happens in the H2O molecule:

Hydrogen here has +1 as oxidation state, while Oxygen is -2

Therefore:

The hydrogen molecule goes from 0 to + 1, so it lost electrons, and according to our description above is the reducing agent. Oxygen would be then the oxidizing agent, because its oxidation state goes from 0 to -2, it gained electrons.