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A 2 g sample containing only CO and CO₂ is treated with excess I₂O₅. If 2.54 g of I₂ is obtained, what is the mass percentage of CO₂ in the original sample?

1. 35
2. 70
3. 30
4. 60

Correct answer: 30

Solution

I2 = 2.54/254 = 0.01 mol; 5CO -> 1 I2, so CO = 0.05 mol = 1.4 g, CO2 = 0.6 g -> 30% CO2. Stored 70 is wrong.

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