Solids, Liquids And Gases
Visão Geral
Put an ice cube on a warm plate and you watch a solid with a fixed shape turn into a liquid that flows into every dent in the china, and then into a gas you cannot see at all. Nothing has been added and nothing has been taken away. The same water particles are there at the end as at the start. All that has changed is how closely those particles are held and how freely they can move.
This lesson gives you the model chemists use to explain that, and then makes you use it. You will describe how particles sit and travel in each of the three states, name every one of the changes between them, work out why a thermometer stops climbing halfway through melting even though the flame is still on, explain what creates the pressure inside a sealed container of gas, and read the evidence that particles are real and moving from three diffusion experiments you can watch happen on a bench. It is the first chemistry topic on this course and it is quietly the most reused: the same sentences come back on Paper 2 inside questions about rates, about melting points and about structure, and the same model turns up again on Paper 3 under a physics heading.
Objetivos
- Matter can be classified in terms of the three states of matter. Students should be familiar with states of matter and be able to name each inter-conversion process. They should be able to describe and explain their inter-conversion in terms of how the particles are arranged and their movement. They should understand the energy changes that accompany changes of state.
- Evidence for the existence of particles can be obtained from simple experiments. Students should be familiar with simple diffusion experiments such as Br2/air, NH3/HCl, KMnO4/water.
Mapa mental
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Nota de Aula
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Avaliação da Lição
Parabéns por concluir a lição em Solids, Liquids And Gases. Agora que você explorou o conceitos e ideias-chave, é hora de colocar seu conhecimento à prova. Esta seção oferece uma variedade de práticas perguntas destinadas a reforçar sua compreensão e ajudá-lo a avaliar sua compreensão do material.
Irá encontrar uma mistura de tipos de perguntas, incluindo perguntas de escolha múltipla, perguntas de resposta curta e perguntas de redação. Cada pergunta é cuidadosamente elaborada para avaliar diferentes aspetos do seu conhecimento e competências de pensamento crítico.
Use esta secção de avaliação como uma oportunidade para reforçar a tua compreensão do tema e identificar quaisquer áreas onde possas precisar de estudo adicional. Não te deixes desencorajar pelos desafios que encontrares; em vez disso, vê-os como oportunidades de crescimento e melhoria.
- Which description matches the particles in a liquid? A. Held in a fixed regular pattern and able only to vibrate B. Close together but disordered, sliding past one another C. Far apart and moving rapidly and randomly in all directions D. Far apart and held in a fixed regular pattern Answer: B
- Which process changes a solid directly into a gas without a liquid forming? A. Condensation B. Evaporation C. Sublimation D. Freezing Answer: C
- A pure solid is heated steadily. Why does its temperature stay constant while it is melting? A. No energy is being supplied during that time B. The energy supplied is used to overcome the forces of attraction between particles C. The particles stop moving completely while melting D. The thermometer responds too slowly to record the change Answer: B
- In the ammonia and hydrogen chloride experiment, the white ring forms nearer the hydrochloric acid end of the tube. Why? A. Ammonia particles have a greater relative molecular mass B. Hydrogen chloride is denser than the air in the tube C. Ammonia particles have a smaller relative molecular mass and so diffuse faster D. Hydrogen chloride is released more slowly from the cotton wool Answer: C
- A gas is sealed in a rigid container and then warmed. Why does its pressure increase? A. The individual gas particles become larger B. The particles strike the walls more often and with greater force C. The number of gas particles in the container increases D. The container contracts as it is warmed Answer: B
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