Question

The chemical equation for the formation of water from its elements is
`2H_2 + O_2 \rightarrow 2H_2O`. If 2.1 mol O₂ are used, how many moles of H₂ are needed?

Answer 1

4.2

Step-by-step explanation:

First we consider the chemical equation. In the chemical equation, we can see that 2 moles of hydrogen gas required a single mole of oxygen gas.

Now, we are told to get the number of moles of hydrogen gas are needed. We already know that the mole ratio of hydrogen to oxygen is 2:1

So mathematically, using the mole ratios expression,

X:2.1 = 2:1

X/2.1 = 2/1

x * 1 = 2.1 * 2

x = 4.2 moles