Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Diffusion in gases
19 practice questions
Practice questions
1–8 of 8 · Normal
Question 1
2 marks · Normal
Answer and see the solution →Explain what is meant by diffusion in gases, using the idea of particles.
Question 2
4 marks · Normal
Answer and see the solution →(a)[1 mark]Figure 1 shows an apparatus used to investigate the diffusion of bromine gas.
Apparatus for diffusion of bromine gas State what you would observe if the lid between the two gas jars is removed.
(b)[2 marks]Explain why the observation described in (a) happens, using ideas about particles.
(c)[1 mark]Suggest why the bromine gas eventually spreads throughout both jars.
Question 3
3 marks · Normal
Answer and see the solution →Two cotton wool plugs, one soaked in concentrated ammonia solution and the other in concentrated hydrochloric acid, are placed at opposite ends of a long glass tube.
After some time, a white ring of ammonium chloride forms closer to the hydrochloric acid end.
Explain why the white ring forms closer to the hydrochloric acid end rather than in the middle. Use ideas about particles and diffusion.
Question 4
1 mark · Normal
Answer and check →Which statement best describes diffusion in gases?
- A.Particles move from a region of low concentration to high concentration.
- B.Particles remain completely still until energy is added.
- C.Particles move from a region of high concentration to low concentration.
- D.Particles only move if they are liquids.
Question 5
2 marks · Normal
Answer and see the solution →A scent is sprayed at one end of a classroom. After a short time, the scent can be detected throughout the room.
Explain why the scent spreads through the room, using the particle model.
Question 6
4 marks · Normal
Answer and see the solution →Solid carbon dioxide (dry ice) turns directly into a gas at room temperature.
(a)[1 mark]What name is given to this change of state?
(b)[2 marks]A lump of dry ice is placed in a beaker at one end of a room. After some time, people at the other end can notice the effects of carbon dioxide.
Explain, using a particle model, why carbon dioxide gas is detected throughout the room.
(c)[1 mark]Why is no liquid seen during this process?
Question 7
3 marks · Normal
Answer and see the solution →In a laboratory experiment, students observe the diffusion of two gases through the air along a glass tube: ammonia (NH₃) is released at one end and hydrogen chloride (HCl) at the other. A white ring of ammonium chloride (NH₄Cl) forms 26 cm from the ammonia end and 14 cm from the hydrogen chloride end after several minutes.
Use the information to:
(a)[1 mark]Calculate the total length of the glass tube.
(b)[2 marks]Explain, using the particle model, why the white ring forms closer to the hydrogen chloride end than to the ammonia end.
Question 8
4 marks · Normal
Answer and see the solution →A teacher sets up the experiment shown below to demonstrate diffusion in gases. Two gas jars are stacked as shown: the lower jar contains brown bromine gas, and the upper jar contains clear air. The lids are removed at time t = 0, and observations are made over the next 10 minutes.
Two gas jars (one above the other), lids labelled. Lower jar contains brown bromine gas, upper jar contains colourless air. The observations are recorded in the table:
Observations of diffusion of bromine and air Time after removing lids (min) Description of appearance 0 Lower jar brown, upper jar clear 2 Brown colour starts to move up 5 Upper jar pale brown 10 Both jars evenly light brown (a)[1 mark]Describe how the appearance of the gas jars changes over time. Use information from the table.
(b)[2 marks]Explain why the brown colour eventually becomes evenly spread in both jars.
(c)[1 mark]Give one reason, using the particle model, why the process takes several minutes rather than happening instantly.