Extended
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Flashcards · 0620 · Topic 1
States of matter flashcards
14 cards on Topic 1, subtopics 1.1 to 1.2. Pick a subtopic or study them all.
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1.1 Solids, liquids and gases
- Particles in a solid: arrangement and movement
- Close together in a regular arrangement. They vibrate about fixed positions.
- Particles in a liquid: arrangement and movement
- Close together in an irregular arrangement. They move around, sliding past each other.
- Particles in a gas: arrangement and movement
- Far apart in a random arrangement. They move quickly in all directions.
- Melting point
- The temperature at which a solid becomes a liquid.
- Boiling point
- The temperature at which a liquid becomes a gas throughout, forming bubbles.
- Evaporation
- Liquid to gas at the surface only, at any temperature below the boiling point.
- Name the change of state: gas → liquid, and liquid → solid
- Gas → liquid: condensation. Liquid → solid: freezing (solidification).
- A gas at constant pressure is heated. What happens to its volume? A gas at constant temperature is compressed (pressure increased). What happens to its volume?
- Heating: the volume increases. Increasing the pressure: the volume decreases.
- Why is a heating curve flat while a substance melts or boils?Extended
- The energy supplied goes into overcoming the forces of attraction between particles, not into raising their kinetic energy, so the temperature stays constant.
- Explain why a gas expands when heated at constant pressureExtended
- The particles gain kinetic energy and move faster, so they hit the container walls harder and more often. The gas expands until the pressure is back to its original value.
1.2 Diffusion
- Diffusion
- The net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient, as a result of their random motion.
- Effect of temperature on the rate of diffusion
- Higher temperature → faster diffusion, because the particles move faster.
- Effect of relative molecular mass (Mr) on the rate of diffusion of a gasExtended
- Lower Mr → faster diffusion. Lighter particles move faster at the same temperature.
- Ammonia and hydrogen chloride diffuse from opposite ends of a tube. Where does the white ring form, and why?Extended
- Nearer the hydrogen chloride end. NH₃ (Mr 17) is lighter than HCl (Mr 36.5), so it diffuses faster and travels further. The white solid is ammonium chloride.