Question

consider the combustion of ethane reaction below for the next two questions.
2c₂h₆(g) + 7o₂(g) → 4co₂(g) + 6h₂o(g)
reaction is at standard temperature and pressure and all reagents are in the gas phase.
if we react 14 moles of oxygen with 5 moles of ethane, how many moles of carbon dioxide would we make?
options: 8, 16, 4, 12

Explanation:

Step1: Identify limiting reactant

From the balanced equation: $2\text{C}_2\text{H}_6(g) + 7\text{O}_2(g)
ightarrow 4\text{CO}_2(g) + 6\text{H}_2\text{O}(g)$
Moles of $\text{O}_2$ needed for 5 mol $\text{C}_2\text{H}_6$:
$\text{Required } \text{O}_2 = 5\ \text{mol} \times \frac{7}{2} = 17.5\ \text{mol}$
We only have 14 mol $\text{O}_2$, so $\text{O}_2$ is limiting.

Step2: Calculate $\text{CO}_2$ from $\text{O}_2$

Mole ratio of $\text{CO}_2$ to $\text{O}_2$ is $\frac{4}{7}$.
$\text{Moles of } \text{CO}_2 = 14\ \text{mol} \times \frac{4}{7}$

Answer:

8