Question

3. Which of the following statements best explains why nitrogen gas at STP is less dense than Xe Has at STP? a) Because Xe is a noble gas, there is less tendency for the Xe atoms to repel one another, so they pack more densely in the gas state. b) Xe atoms have a higher mass than N2 molecules, Because both gases at STP have the same number of molecules per unit volume, the Xe gas must be denser, c) The Xe atoms are larger than N2 molecules and thus take up a larger fraction of the space occupied by the gas. d) Because the Xe atoms are much more massive than the N2 molecules, they move more slowly and thus exert less upward force on the gas container and make the gas appear denser. 4. A mixture of gases contains 0.75 mol N2, 0.30 mol O2, and 15 mol CO2. If the total pressure of the mixture is 2.15 atm, what is the partial pressure of each component?

Answer 1

Ans 3 : b) Xe atoms have a higher mass than N2 molecules. Because both gases at STP have the same number of molecules per unit volume, the Xe gas must be denser.

The molar volume of all gases at STP is ideally 22.4 liters. So if the molar mass of Xenon gas is more than nitrogen gas , it mass per unit volume will be higher and hence denser than nitrogen.