Graham's Law

Grahams law of effusion explains why some molecules have a higher velocity rate than others. Out of the following substances which gas will have the highest velocity ?

• Ammonia

• Hydrogen

• Chlorine

• Nitrogen

How much faster will He(g) travel than O₂(g)?

• 4 times faster

• 2.8 times faster

• 0.35 times faster

• 0.125 times faster

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 if they are at the same conditions?

• because O₂ has more kinetic energy

• because O₂ has a smaller molar mass

• because O₂ has a higher temperature

• they will effuse the same because the temperature is fixed

Which travels faster? CO₂ or Ar?

• CO₂

• Ar

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

If the molar mass of gas 1 is 4.0 grams per mole and the molar mass of mass 2 is 10.0 grams per mole, what is the ratio of their speeds of diffusion?

• 1.6:1

• 2.5:1

• 25:1

• 0.0253:1

Lighter gases have a ________________ rate of effusion.

• faster 

• slower

• rate of effusion does not depend on mass.

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

How much faster will gaseous hydrogen effuse than gaseous chlorine under the same physical conditions?

• 5.92

• 5.95

• 0.03

• 1.00