Effusion Practice Problems

True or False. Helium-filled balloon loses pressure faster than an air-filled balloon because helium has a smaller molecular mass than the components of air.

Determine the molecular weight and identity of a gas that diffuses 1.12 times faster than Ar through a porous membrane.

An unidentified gas diffuses 1.33 times more slowly than Cl₂ through a porous membrane. What is the gas's molecular weight?

Calculate the ratio of the diffusion rates and arrange the gases in order of their speed of diffusion: HBr, Cl₂, Kr

⁷⁹Br and ⁸¹Br are isotopes of bromine. How do the diffusion rates of (⁷⁹Br)₂, (⁸¹Br)₂, and ⁷⁹Br⁸¹Br compare?

The apparatus shown here has three gas-filled containers and two empty containers, all connected with a hollow tube. Identify the distribution of atoms in each container when the valves are opened and the gases are allowed to mix at a constant temperature. Assume that the volume of the tube connecting the containers is negligible. 

Hydrogen and Bromine both have two stable isotopes. Hydrogen has ¹H and ²H isotopes while Bromine has ⁷⁹Br and ⁸¹Br isotopes. 

This means that the acid HBr has 4 different combinations for molecules: ¹H⁷⁹Br, ¹H⁸¹Br, ²H⁷⁹Br, and ²H⁸¹Br. List the molecules from the lowest to the highest rate of effusion. 

Identify which of the following statements are false. 

i) The molecules from food responsible for its smell travel to your nose by the process of diffusion. 

ii)  F₂ will effuse faster than Kr.

iii) The higher the molar mass, the higher the effusion rate. 

iv) Effusion and diffusion are different processes.

v) Heavier molecules take more time to effuse. 

Consider the following experiment: 

A Kr gas was allowed effuse through a small hole under constant pressure. The 2 L sample of Kr took 96.0 s to effuse. Another gas of unknown identity went through the same conditions. It took a 2 L sample of the unknown gas 55.5 s to effuse. Calculate the molar mass of the unknown gas. 

Under the same conditions of temperature and pressure, molecules of an acid in the gas phase effuse through a small hole at 0.702 times the rate of effusion of Ar gas. Calculate the molecular formula of the acid if it only has one hydrogen atom and one other atom.

Ammonium bromide can be prepared by the direct action of hydrogen bromide on ammonia.

NH₃ + HBr → NH₄Br

Now consider the following experiment. A 5 ft tube filled with Kr at 1.0 atm with the ends covered with a rubber stopper. 

NH₃ and HBr were then simultaneously introduced at opposite ends of the tube. A ring of solid forms where the gases meet due to the mentioned reaction.

Approximately where in the tube would you expect the ring to form? 

Arrange in order of increasing rate of effusion: Cl₂, Ar, HI.

Under the same conditions, 20.0 mL of Kr gas diffuses in 1.5 min. while 16.0 mL of an unknown hydrocarbon diffuses in 1.0 min. Determine the molecular formula of the hydrocarbon.

The isotope Helium-3 contains unique physical properties and is used ultralow temperature experiments. He-3 (3.01603 amu) is separated from the more abundant He-4 (4.00260 amu) via gaseous diffusion. Calculate the ratio of effusion rates for He-3 and He-4.

The rates of effusion of oxygen to an unknown gas have a ratio of 1.488. Determine the identity of the other gas.

How fast would ammonia (NH₃) molecules effuse compared to carbon dioxide (CO₂) molecules? Determine the ratio of rates of effusion and answer using three significant figures.

It takes 54 seconds for N₂O gas to effuse from a container. How much time it would take for the same amount of I₂ gas to effuse from the same conditions?

Among C₃H₈, Xe, and PF₅, which gas would effuse more rapidly than O₂ at STP?

A sample of CO₂ effuses from a container in 57.0 seconds. How long will it take the same amount of gaseous Br₂ to effuse from the same container under identical conditions?