Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
States of Matter
102 practice questions
Topics covered
Practice questions
21–30 of 44 · Normal
Question 21
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 22
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 23
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 24
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 25
2 marks · Normal
Answer and see the solution →State the meaning of the following terms as used in chemistry:
(a)[1 mark]solute
(b)[1 mark]solvent
Question 26
4 marks · Normal
Answer and see the solution →The graph below shows the solubility of two different salts (potassium nitrate and sodium chloride) in water as the temperature increases.
(a)[1 mark]Using the graph, estimate the solubility of potassium nitrate in water at 30°C.
(b)[1 mark]State which salt is more soluble at 0°C. Justify your answer using data from the graph.
(c)[2 marks]Explain what is meant by a 'solubility curve'.
Question 27
3 marks · Normal
Answer and see the solution →A student wants to find the solubility of copper(II) sulfate in water at 30°C. She carries out the following experiment:
1. Weighs an empty evaporating basin: 28.60 g 2. Adds a known mass of saturated copper(II) sulfate solution at 30°C to the basin: total mass 62.10 g 3. Evaporates all the water. The mass of evaporating basin plus copper(II) sulfate crystals after heating is 36.10 g
Calculate the solubility of copper(II) sulfate in water at 30°C in g per 100 g water, giving your answer to 2 significant figures.
Question 28
1 mark · Normal
Answer and check →Which precaution should be taken to ensure an accurate measurement of solubility during the experiment to find the solubility of a salt in water?
- A.Use cold tap water to dissolve the salt
- B.Pour undissolved solid into the evaporating basin with the solution
- C.Weigh the evaporating basin before and after adding the solution
- D.Include some dry solid in the final weighing
Question 29
2 marks · Normal
Answer and see the solution →State the meaning of the following:
(a)[1 mark]solution
(b)[1 mark]saturated solution
Question 30
4 marks · Normal
Answer and see the solution →The graph below shows the solubility curves of two substances, ammonium chloride and sodium chloride, in water.
(a)[2 marks]Compare how the solubility of ammonium chloride and sodium chloride changes as temperature increases.
(b)[1 mark]Estimate the solubility of ammonium chloride at 50°C using the graph.
(c)[1 mark]Which substance is more soluble at 0°C?