This question is about solids, liquids and gases.
(a) The list gives the names of nine substances which are solids at room temperature.
a ceramic
aluminum
anhydrous cobalt(II) chloride
anhydrous copper(II) sulfate
calcium oxide
graphite
iodine
iron
sodium
Answer the following questions about these substances.
Each substance may be used once, more than once or not at all.
State which substance:
(i) turns pink when water is added to it
(ii) is a non-metal which is used as a lubricant
(iii) is used to neutralize acidic industrial waste
(iv) is extracted from bauxite
(v) is used as an electrical insulator.
(b) Some changes of state of sodium are shown.
(i) State the names of the changes of state represented by A and B.
(ii) Use the kinetic particle model to describe the arrangement and separation of the particles in:
solid sodium
liquid sodium
▶️ Answer/Explanation
(a)
(i) Anhydrous cobalt(II) chloride turns pink when water is added due to the formation of hydrated cobalt(II) chloride.
(ii) Graphite is a non-metal with layered structure, making it an effective lubricant.
(iii) Calcium oxide neutralizes acidic waste as it is a basic oxide that reacts with acids.
(iv) Aluminum is extracted from bauxite ore through the Bayer process.
(v) Ceramic is used as an electrical insulator due to its high resistivity.
(b)(i)
A: Melting (solid to liquid)
B: Condensation (gas to liquid)
(b)(ii)
Solid sodium: Particles are closely packed in a regular arrangement with minimal movement.
Liquid sodium: Particles are close but disordered, allowing flow while maintaining proximity.
Matter can exist as solid, liquid or gas. The arrows show some changes of state
(a) Name the changes of state represented on the diagram.
(b) Explain why energy has to be supplied to turn a liquid into a gas.
(c) The diagrams represent the same number of particles of a gas in two containers, D and E, which have different volumes. The two containers are at the same temperature.
In which container will the pressure be higher? Explain your answer.
▶️ Answer/Explanation
(a)
(i) Melting: Transition from solid to liquid as heat energy breaks the rigid structure.
(ii) Sublimation: Direct change from solid to gas without passing through the liquid phase.
(iii) Condensation: Gas particles lose energy and transition into liquid state.
(b) Energy is required to overcome intermolecular forces between liquid particles and allow them to escape as gas.
(c) Container E has higher pressure because the same number of particles in a smaller volume results in more frequent collisions with the walls.
Final Answer:
2(a)(i) melt(ing)
2(a)(ii) sublimation / sublime
2(a)(iii) condensing/ condensation
2(b) overcome / break the attractive forces
2(c) E AND particles hit the walls (of the container) more often