Question

2co(g) + o₂(g) → 2co₂(g)
9.0 l of o₂ react with excess co at stp. how many moles of co₂ form during the reaction?
? mol co₂

Explanation:

Step1: Find moles of O₂ at STP

At STP, 1 mol gas = 22.4 L.
Moles of O₂ = $\frac{9.0\ \text{L}}{22.4\ \text{L/mol}} \approx 0.4018\ \text{mol}$

Step2: Relate O₂ to CO₂ via stoichiometry

Reaction ratio: 1 mol O₂ → 2 mol CO₂.
Moles of CO₂ = $0.4018\ \text{mol O₂} \times \frac{2\ \text{mol CO₂}}{1\ \text{mol O₂}} \approx 0.80\ \text{mol}$

Answer:

0.80