A given volume of oxygen diffused through a porous partition in 8 seconds. How long would it take the same…

Analyze the question: This is about Graham's Law of diffusion. We compare the time for equal volumes of O₂ and CO₂ to diffuse under the same conditions.

Concept: Graham's Law says the rate of diffusion is inversely proportional to the square root of molar mass (density). For equal volumes, time is directly proportional to the square root of molar mass:

t₁/t₂ = √(M₁/M₂)

Solution:

• Molar mass of O₂ = 2 × 16 = 32
• Molar mass of CO₂ = 12 + (2 × 16) = 44

Let t(CO₂) be the time for CO₂:

t(CO₂)/t(O₂) = √(44/32)

t(CO₂) = 8 × √(1.375)

√1.375 ≈ 1.1726

t(CO₂) = 8 × 1.1726 ≈ 9.38 seconds ≈ 9.4 seconds

Answer: C. 9.4 seconds.

Tip: For equal volumes, the heavier gas takes longer, so your answer must be greater than 8 seconds. This lets you eliminate A and B immediately. Remember: time ∝ √M, and rate ∝ 1/√M.