States Of Matter All subtopics

A gas has no fixed shape; a gas has no fixed volume — it fills the available space; a gas is easily compressed / a solid cannot be compressed.

Particles in a liquid can slide past each other, so the liquid flows to match the container’s shape; the particles remain close together with forces of attraction between them, so the total volume stays constant.

Particles are irregularly arranged and mostly touching; they move around each other / slide past one another.

Gas particles are far apart with large spaces between them, so a given volume of gas contains far fewer particles than the same volume of a solid; the solid has closely packed particles with very small separation, resulting in a much greater mass per unit volume.

Condensing / condensation.

Boiling occurs at a fixed temperature (the boiling point) throughout the liquid; evaporation occurs at any temperature below the boiling point and only at the surface of the liquid. Both convert liquid to gas, but boiling requires a specific temperature while evaporation does not.

The volume of the gas decreases; the gas particles are pushed closer together.

Heating increases the kinetic energy of the gas particles, so they move faster and collide with the walls of the container more forcefully and more frequently; the particles push outward with greater force, causing the gas to expand and occupy a larger volume.

The temperature remains constant during boiling; the energy supplied is used to overcome the forces of attraction between particles rather than to increase their kinetic energy.

The first flat section represents melting — the solid is changing to a liquid at a constant temperature; energy is being used to overcome some of the forces of attraction between particles so they can move around each other. The second flat section represents boiling — the liquid is changing to a gas at a constant temperature; energy is being used to completely overcome the remaining forces of attraction so particles can move freely and far apart.

Increasing the external pressure forces the gas particles closer together; the particles are pushed into a smaller space; the temperature is constant so the particles still move at the same speed, but the same number of particles now occupies a smaller volume.

The gas particles inside the balloon absorb energy from the warm surroundings and gain kinetic energy; they move faster and collide with the inner walls of the balloon more forcefully and more frequently; the increased force of collisions pushes the flexible walls outward; the volume of the balloon increases.

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration; due to the random motion of particles in a gas or liquid.

Water molecules and ink particles are in constant random motion due to kinetic energy; ink particles move from the region of higher ink concentration near the drop to regions of lower ink concentration throughout the beaker; the water is warm, so particles have more kinetic energy and move faster; therefore diffusion occurs more quickly than in cold water.

The greater the relative molecular mass of a gas, the slower its rate of diffusion; because heavier particles move more slowly at a given temperature.

Ammonia has a lower relative molecular mass (Mᵣ = 17) than hydrogen chloride (Mᵣ = 36.5); therefore ammonia particles move faster and diffuse a greater distance along the tube in the same time; the two gases meet closer to the HCl end; they react to form ammonium chloride, NH₃(g) + HCl(g) → NH₄Cl(s), which appears as a white ring.