The rate of effusion of an unknown gas was measured and found to be 10.7 mL/min.Under identical conditions,the rate of effusion of pure oxygen (O₂)gas is 12.6 mL/min.Based on this information,the identity of the unknown gas could be: A) N₂CH₂OF₂ B) CO₂N₂O C) NO D) C₂H₆ E) none of these

Question

Quizplus · Accepted Answer

The rate of effusion of a gas is inversely proportional to the square root of its molar mass. Therefore, we can calculate the ratio of the molar mass of the unknown gas to that of oxygen:
(molar mass of unknown gas / molar mass of oxygen) = (rate of effusion of oxygen / rate of effusion of unknown gas) ^2
Plugging in the given values, we get: 
(molar mass of unknown gas / 32 g/mol) = (12.6 mL/min / 10.7 mL/min)^2
Simplifying, we get:
molar mass of unknown gas = 32 g/mol * (10.7 mL/min / 12.6 mL/min)^2
Calculating this gives us a molar mass of approximately 22 g/mol. Looking at the choices, only option B has a gas with a molar mass close to this value - nitrogen (N2) has a molar mass of approximately 28 g/mol and oxygen (O2) has a molar mass of approximately 32 g/mol, so a mixture of these gases (option B) would have a molar mass close to 22 g/mol. Therefore, the correct answer is B.

The Rate of Effusion of an Unknown Gas Was Measured