Graham's Law

The rate of effusion is _______________ proportional to the square root of its' molar mass. 

• Directly
• Inversely 

Lighter gases have a ________________ rate of effusion.

• faster 
• slower
• rate of effusion does not depend on mass.

Which of the following would have a faster rate of effusion: 15g of Kr or 15g of N₂?

• Kyrpton
• Nitrogen
• Both would have the same rate of effusion

Effusion is

• used to describe the combustibility of a gas.
• ability of a gas to escape through a tiny opening
• what occurs after diffusion.
• the ability of a gas to mix with other gases.

The rate of effusion of water vapor is 0.391 and the rate of effusion of propane is 0.251 at the same temperature and pressure.  What is the molar mass of propane? (write the formula and show your work)

• 44.0 g/mol
• 6.63 g/mol
• 0.37 g/mol
• 28.2 g/mol

Identify the factor that determines rates of diffusion and effusion for different molecules at a given temperature.

• Size of the molecules

• Polarity of the molecules

• Temperature of the gas

• Molar mass of the gas

Effusion and diffusion rates are inversely proportional to the square root of the molar mass of the gas.

• True

• False

why would O₂ effuse faster than CO₂ in the same room

• because it has more energy
• because it has a greater molar mass
• because oxygen has a higher temperature
• they will effuse the same because the temperature is fixed

Which of the following gases will effuse most slowly under the same physical conditions?
Don't forget to check for diatomics!

• Hydrogen
• Chlorine
• Ammonia (NH₃)
• Bromine

Use Graham’s Law to calculate fast O₂ gas will effuse compared to Cl₂. 

• O₂ effuses 1.5x faster than Cl₂
• O₂ effuses 0.11x as fast as Cl₂
• O₂ effuses 1.1x faster than Cl₂
• O₂ effuses 0.15x as fast as Cl₂