The density of an unknown gas is 1.72 g/L at 750.0 torr and 30.0°C. Which of the following could be the unknown gas?

Question

Quizplus · Accepted Answer

To determine which gas could be the unknown gas, we need to compare its molar mass with the molar masses of the gases listed. We can use the ideal gas law to calculate the molar mass of the unknown gas: PV = nRT n = mass / molar mass PV = (mass / molar mass) RT molar mass = (mass / PV) RT Substituting the given values: molar mass = (1.72 g/L / 750.0 torr) (0.08206 L atm/mol K) (303 K) = 55.9 g/mol Now we can compare this molar mass with the molar masses of the gases listed: A) CS₂: This is not a valid chemical formula. B) NO: Molar mass = 30 g/mol, which is much less than 55.9 g/mol. C) N₂O: Molar mass = 55.8 g/mol, which is very close to 55.9 g/mol. This could be the unknown gas. D) NH₃: Molar mass = 59 g/mol, which is greater than 55.9 g/mol. E) NO₂: Molar mass = 46 g/mol, which is much less than 55.9 g/mol. Therefore, the best choice(s) for the unknown gas is C.

The Density of an Unknown Gas Is 1