4.1-9 Graham's Law

Grahams law refers specifically to

• the rate of diffusion

• the rate of effusion

• the temperature of gases

• the partial and total pressures of gases in a sample.

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 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

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

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

why would O₂ effuse faster than CO₂ in the same room

• because O₂ has more energy

• because CO₂ has a greater molar mass

• because oxygen has a higher temperature

• they will effuse the same because the temperature is fixed

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

An unknown gas diffuses 0.25 times as fast as helium gas (He). What is the molecular mass of the unknown gas? 

• 64 g/mol
• 16 g/mol
• 32 g/mol
• 4 g/mol