Worksheet: Graham's Law

In this worksheet, we will practice using Graham's law to calculate the relative effusion rates of gases from the square roots of the molar masses.

Q1:

An unknown hydrocarbon gas effuses 1.66 times more rapidly than CO2.

What is the molar mass of the unknown gas?

What is the likely identity of the gas?

  • A C H 3 6
  • B C H 2 2
  • C C H 4
  • D C H 2 6
  • E C H 2 4

Q2:

Which of the following gases diffuses faster than oxygen?

  • A H S 2
  • B N O 2
  • C C H 2 2
  • D C l 2
  • E F 2

Q3:

A balloon filled with helium gas is found to take 6.00 hours to deflate to 50% of its original volume. How long will it take for an identical balloon filled with the same volume of hydrogen gas (instead of helium) to decrease its volume by 50%?

  • A3.01 hours
  • B4.98 hours
  • C8.45 hours
  • D1.34 hours
  • E4.26 hours

Q4:

When two cotton plugs, one moistened with ammonia and the other with hydrochloric acid, are simultaneously inserted into opposite ends of a glass tube that is 87.0 cm long, a white ring of NHCl4 forms where gaseous NH3 and gaseous HCl first come into contact. Ammonia and hydrochloric acid react together according to the equation shown. NH()+HCl()NHCl()34ggs

How far from the end with ammonia would you expect the ring to form?

  • A 29.0 cm
  • B 51.7 cm
  • C 72.1 cm
  • D 43.5 cm
  • E 35.29 cm

Q5:

It takes 243 s for 4.46×10 molXe to effuse through a tiny hole. Under the same conditions, how long will it take 4.46×10 molNe to effuse?

Q6:

What is the ratio of the rate of effusion of hydrogen to the rate of effusion of oxygen?

  • A 2 1
  • B 3 2
  • C 4 3
  • D 4 1
  • E 1 4

Q7:

An equal number of moles of fluorine and helium diffuse into a chamber with no change in pressure or temperature. Calculate to 2 significant figures the diffusion rate of fluorine as a percentage of the diffusion rate of helium?

  • A 4 6 %
  • B 3 5 %
  • C 1 6 %
  • D 3 2 %
  • E 1 1 %

Q8:

An equal number of moles of nitrogen and a second gas diffuse into a chamber with no change in pressure or temperature. What is the molar mass of the second gas to the nearest gram per mole if its diffusion rate is two-thirds less than that of nitrogen?

Q9:

An equal number of moles of argon and a second gas diffuse into a chamber with no change in pressure or temperature. What is the molar mass of the second gas to the nearest gram per mole if its diffusion rate is 41% greater than that of argon?

Q10:

An equal number of moles of neon-20 and a second gas diffuse into a chamber with no change in pressure or temperature. Which of the following is a possible molecular formula for the second gas if its diffusion rate is 56.2% lower than that of neon-20?

  • A C H S 2 6
  • B H B r O
  • C S i F 4
  • D N O 2
  • E H C l

Q11:

An equal number of moles of oxygen and hydrogen gas diffuse into a chamber with no change in pressure or temperature. By approximately what factor does the diffusion rate of oxygen differ from that of hydrogen?

  • A 1 8
  • B 1 1 6
  • C 1 3 2
  • D 1 8
  • E 1 4

Q12:

The molecules in gas A have molecular mass 𝑀A and an average speed 𝑣A, while the molecules in gas B have molecular mass 𝑀B and an average speed 𝑣B.

If the gases are at the same temperature, how may the ratio 𝑣/𝑣AB be expressed in terms of 𝑀A and 𝑀B?

  • A 𝑀 𝑀 A B
  • B 𝑀 𝑀 B A
  • C 𝑀 𝑀 A B
  • D 𝑀 𝑀 A B
  • E 𝑀 𝑀 B A

If the temperature of gas A is doubled and the temperature of gas B remains constant, by what factor does the ratio 𝑣/𝑣AB increase?

  • A 1 2
  • B 1 2
  • C4
  • D 2
  • E2

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