Solids, Liquids and GasesCambridge IGCSE Chemistry: Flashcards

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What are the three distinguishing properties of solids?

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What are the three distinguishing properties of solids?: Solids have a fixed shape, fixed volume, and are not compressible. The particles are tightly packed in a regular, ordered arrangement.
State the three distinguishing properties of liquids.: Liquids have a fixed volume but no fixed shape (they take the shape of their container). They are slightly compressible. The particles are closely packed but in a random arrangement.
What are the three distinguishing properties of gases?: Gases have no fixed shape and no fixed volume (they spread to fill their container). They are highly compressible. The particles are far apart and move rapidly in random directions.
Describe the structure of a solid in terms of particle separation, arrangement and motion.: In solids, particles are very close together with little separation. They are arranged in a regular, fixed pattern. Particles vibrate in fixed positions but do not move around.
Describe the structure of a liquid in terms of particle separation, arrangement and motion.: In liquids, particles are close together with small separation between them. They are randomly arranged. Particles move around randomly and can slide past each other.
Describe the structure of a gas in terms of particle separation, arrangement and motion.: In gases, particles are far apart with large separation between them. They are randomly arranged with no fixed pattern. Particles move rapidly and randomly in all directions.
Define melting.: Melting is the change of state from solid to liquid. It occurs when a solid is heated and particles gain enough kinetic energy to overcome the forces holding them in fixed positions.
Define boiling and evaporation. What is the key difference between them?: Boiling is the rapid change of state from liquid to gas at a fixed temperature (the boiling point), occurring throughout the liquid. Evaporation is the slower change of state from liquid to gas at any temperature, occurring only at the surface.
Define freezing.: Freezing is the change of state from liquid to solid. It occurs when a liquid is cooled and particles lose kinetic energy, slowing down until they can no longer overcome intermolecular forces and form a fixed structure.
Define condensing.: Condensing is the change of state from gas to liquid. It occurs when a gas is cooled and particles lose kinetic energy, moving more slowly until intermolecular forces pull them together to form a liquid.
How does temperature affect the volume of a gas? Explain using kinetic particle theory.: As temperature increases, gas particles move faster and collide with container walls more forcefully and more frequently, increasing pressure. If the container volume is fixed, pressure increases. If the container can expand, volume increases. According to kinetic particle theory, particles have greater kinetic energy at higher temperatures.
How does pressure affect the volume of a gas? Explain using kinetic particle theory.: As pressure on a gas increases, the volume decreases (at constant temperature). This is because increased external pressure compresses the gas, forcing particles closer together. According to kinetic particle theory, when particles are closer, they collide more frequently, so less external pressure is needed to maintain equilibrium, causing volume to decrease.
What does a heating curve show, and what happens on the flat sections?: A heating curve shows temperature change against time as a substance is heated. On the flat (horizontal) sections, the temperature remains constant even though heat is being added. This occurs during changes of state (melting and boiling) when energy is used to break intermolecular forces rather than increase particle kinetic energy.
Explain what happens to particles during melting in terms of kinetic particle theory.: During melting, particles in a solid gain kinetic energy as temperature increases. This energy allows particles to overcome the strong intermolecular forces holding them in fixed positions. Particles begin to move around more freely, transitioning from an ordered solid structure to the random arrangement of a liquid.
Explain what happens to particles during boiling in terms of kinetic particle theory.: During boiling, particles in a liquid gain sufficient kinetic energy to completely overcome intermolecular forces. Particles escape from the liquid and become separated by large distances, moving rapidly and randomly as a gas. Energy supplied goes into breaking intermolecular bonds, not increasing temperature.
State the relationship between pressure and volume for a gas at constant temperature.: At constant temperature, pressure and volume of a gas are inversely proportional. As pressure increases, volume decreases, and vice versa. This relationship is known as Boyle's Law and can be expressed as P₁V₁ = P₂V₂.