Question

Given this equation: 2 H2 + O2 → 2 H2O, how many moles of O2 are needed to yield 0.3 moles of water?

Answer 1

From the euqation, we can see that 1 mol of O₂ reacts to produce 2 moles of H₂O.

We can use this and rule of three to calculate the answer:

1 mol O₂ --- 2 mol H₂O

x --- 0.3 mol H₂O

So:

`\begin{gathered} (1)/(x)=(2)/(0.3) \\ (x)/(1)=(0.3)/(2) \\ x=(0.3)/(2)=0.15 \end{gathered}`

So, we need 0.15 mol of O₂.