Graham's Law of Effusion

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

Heavier 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 S or 15g of N₂?

• Sulfur

• Nitrogen

• Both would have the same rate of effusion

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

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

how many times faster does He effuse compared to N₂ (He = 4  N₂ = 28)

• 2 times faster

• 65 times faster

• 7 times faster

• 0.377 times faster

Which of the following correctly describes effusion?

• The movement of a gas into an area of higher pressure, always

• The movement of a gas into a vacuum (lower pressure area)

• The mixing of gases

• None of the above

The ratio of the speed of helium to gas X is 16:1. What is the molar mass of gas X? (use 4 g/mol for He)

• 1024

• 256

• 128

• 64

According to Graham's Law of Effusion, if gas A effuses four times faster than gas B, what is the ratio of their molar masses (M_A/M_B)?

• 1:16

• 1:4

• 1:2

• 1:8