# What is the reducing agent in the reaction 2Na + 2H_2O -> 2NaOH + H_2?

Jul 29, 2016

Sodium metal.

#### Explanation:

You're dealing with a redox reaction in which sodium metal, $\text{Na}$, is being oxidized to sodium cations, ${\text{Na}}^{+}$, and hydrogen is being reduced to hydrogen gas, ${\text{H}}_{2}$.

$2 {\stackrel{\textcolor{b l u e}{0}}{\text{Na")_ ((s)) + 2stackrel(color(blue)(+1))("H")_ 2 stackrel(color(blue)(-2))("O")_ ((l)) -> 2stackrel(color(blue)(+1)) ("Na") stackrel(color(blue)(-2))("O") stackrel(color(blue)(+1))("H")_ ((aq)) + stackrel(color(blue)(0))("H}}}_{2 \left(g\right)}$

As you can see, the oxidation state of sodium goes from $\textcolor{b l u e}{0}$ on the reactants' side, to $\textcolor{b l u e}{+ 1}$ on the products' side, which implies that sodium metal is being oxidized.

On the other hand, the oxidation state of hydrogen goes from $\textcolor{b l u e}{+ 1}$ on the reactants' side, to $\textcolor{b l u e}{0}$ on the products' side, which implies that hydrogen is being reduced.

Now, a reducing agent is responsible with reducing a chemical species that takes part in a redox reaction. Similarly, an oxidizing agent is responsible with oxidizing a chemical species that takes part in a redox reaction.

You can thus say that the chemical species that is being oxidized acts as a reducing agent for the chemical species that is being reduced.

In this case, sodium metal is being oxidized, which implies that it is acting as the reducing agent.