# How many moles of water can you form from 4 moles of hydrogen and excess oxygen? 2H2(g) + O2(g)...

## Question:

How many moles of water can you form from 4 moles of hydrogen and excess oxygen?

{eq}2H_2(g) + O_2(g) \to 2H_2O(l) {/eq}

## Balanced Chemical Equations:

The representation of reactions as balanced chemical equations is very useful in computations. The coefficients that are a result of balancing chemical equations provide information on the equivalent number of substances relative to another substance with its corresponding coefficient.

Determine the number of moles of water, {eq}\displaystyle n_{H_2O} {/eq}, that is formed from the given reaction. From the balanced chemical equation,

{eq}\displaystyle 2H_2 + O_2 \to 2H_2O {/eq}

we determine that the number of moles of {eq}\displaystyle H_2 {/eq} corresponds to an equal number of moles of {eq}\displaystyle H_2O {/eq}, such that we relate the number of moles of the substances using the equation as

{eq}\displaystyle n_{H_2} = n_{H_2O} {/eq}

Now, we are given that {eq}\displaystyle n_{H_2} = 4\ mol {/eq} that reacts with {eq}\displaystyle O_2 {/eq}, so we can solve for the number of moles of products as

{eq}\begin{align} \displaystyle n_{H_2} &= n_{H_2O}\\ 4\ mol &= n_{H_2O} \end{align} {/eq}

Therefore, there are also 4 moles of water that is produced in the reaction.