Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Diffusion in gases
19 practice questions
Practice questions
11–19 of 19
Question 11
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 12
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 13
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 14
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 15
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 16
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.
Question 17
2 marks · Hard
Answer and see the solution →A laboratory tube is filled at one end with nitrogen gas and at the other end with a coloured gas, chlorine. After some time, the green colour of chlorine spreads along the tube but it takes a few hours until the colour is even throughout.
Explain, using the particle model, why the spreading takes much longer than if chlorine particles could travel in a straight line from one end to the other.
Question 18
5 marks · Hard
Answer and see the solution →A student investigates the rate of diffusion of hydrogen and air using the apparatus shown. In a sealed glass tube, a small amount of hydrogen is released at one end and air at the other. After some time, the gases mix completely.
(a)[2 marks]Describe, using the particle model, how the hydrogen and air particles move inside the tube during diffusion.
(b)[1 mark]Suggest one reason, in terms of particles, why hydrogen diffuses faster than air.
(c)[2 marks]The tube is cooled to a much lower temperature. Predict and explain the effect this will have on the rate of diffusion, using ideas about particle movement.
Question 19
2 marks · Hard
Answer and see the solution →Explain why, when perfume is sprayed in one corner of a large room, the scent is eventually noticed everywhere in the room. Include reference to the movement of gas particles.