In the formation of carbon dioxide (CO2) from carbon monoxide (CO) and oxygen (O2), how many moles of carbon monoxide are needed to react completely with 7.0 moles of oxygen gas

14 moles of CO are needed in the reaction, to react with 7 moles of O₂

Explanation:

We need to determine the reaction to start:

O₂ (g) + 2CO (g) → 2CO₂ (g)

Now, we state the ratio of reactants:

1 mol of oxygen needs 2 moles of CO, to react and they both, produce 2 moles of CO₂. Therefore the ratio is 1:2

We can make a rule of three to reach the answer:

1 mol of O₂ needs 2 moles of CO to react

Therefore, 7 moles of O₂ must need (7.2) / 1 = 14 moles