Cambridge IGCSE · Chemistry (0620)

Diffusion: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Diffusion.

10 questions26 marksFree, no account

Question 1

1 mark

Given the following relative molecular masses, \( M_r \), which gas will diffuse most slowly at room temperature?
\( H_2 = 2 \)
\( CH_4 = 16 \)
\( Ne = 20 \)
\( SO_2 = 64 \)

Question 2

1 mark

In an experiment, a gas jar of brown nitrogen(IV) oxide gas, \( NO_2 \), is placed upside down on top of a gas jar containing colorless air. After several hours, the brown color has spread uniformly throughout both jars.
Which statement correctly explains this observation using kinetic particle theory?

Question 3

1 mark

Which statement correctly explains why hydrogen gas (\( M_r = 2 \)) diffuses faster than helium gas (\( A_r = 4 \)) at the same temperature?

Question 4

1 mark

What is the term used to describe the net movement of particles from a region of their higher concentration to a region of their lower concentration as a result of their random movement?

Question 5

1 mark

A crystal of purple potassium manganate(VII) is placed at the bottom of a beaker of still water. After several hours, the entire solution turns purple.
Which process is responsible for this observation?

Question 6

2 marks

State the relationship between temperature and the rate of diffusion in a gas.

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Question 7

4 marks

Arrange the following three gases in order of decreasing rate of diffusion at the same temperature: oxygen (\( \text{O}_2 \)), methane (\( \text{CH}_4 \)), and sulfur dioxide (\( \text{SO}_2 \)). Show your reasoning based on relative molecular mass.

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Question 8

6 marks

A porous pot containing air is connected to a U-tube manometer and then surrounded by a beaker of hydrogen gas, \( \text{H}_2 \). Describe and explain the initial movement of the liquid level in the U-tube side closest to the pot.

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Question 9

4 marks

A student places a crystal of purple potassium manganate(VII) at the bottom of a beaker of still water. After several hours, the entire solution turns purple.
(a) Name the process that has occurred.
(b) Use the kinetic particle theory to explain how the purple color spreads.
(c) Predict the effect on the rate of this process if warm water was used instead of cold water.
(d) Explain your prediction in part (c).

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Question 10

5 marks

Explain the relationship between relative molecular mass (\( M_r \)) and the rate of diffusion by comparing oxygen gas (\( O_2 \), \( M_r = 32 \)) and methane gas (\( CH_4 \), \( M_r = 16 \)).
(a) State which gas will diffuse faster at the same temperature.
(b) Explain your answer in terms of particle speed.
(c) Calculate how many times faster/slower the lighter gas is expected to move compared to the heavier gas (qualitative comparison).

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