Why do gases expand more than solids when heated?

Gases expand more than solids when heated due to their weaker intermolecular forces and higher kinetic energy.

In more detail, the behaviour of gases, solids, and liquids when heated is determined by the strength of the forces between their particles and the amount of kinetic energy they possess. Solids have strong intermolecular forces and their particles are closely packed together in a fixed, regular arrangement. This means that when they are heated, the particles vibrate more but cannot move far from their fixed positions, so the expansion is minimal.

On the other hand, gases have very weak intermolecular forces and their particles are far apart from each other, moving freely in all directions. When a gas is heated, the kinetic energy of its particles increases significantly. This causes the particles to move faster and further apart, leading to a large increase in the volume of the gas. This is why gases expand more than solids when heated.

Furthermore, the behaviour of gases when heated can be explained by the ideal gas law, which states that the pressure times the volume of a gas is directly proportional to the temperature of the gas, provided the amount of gas remains constant. This means that if the temperature of a gas increases, the volume of the gas will also increase if the pressure is kept constant. This is not the case for solids, as their volume does not change significantly with temperature due to their strong intermolecular forces and fixed particle arrangement.

In summary, the greater expansion of gases compared to solids when heated is due to the weak intermolecular forces in gases, the high kinetic energy of gas particles, and the principles of the ideal gas law.