Solids, liquids and gases expand when heated. Water expands about four percent when heated from room temperature to its boiling point. The ocean will expand when heated.

Most matter expands when heated and contracts when cooled, a principle called thermal expansion. The average kinetic energy of the particles increases when matter is heated and this increase in motion increases the average distance between its atoms.

When a material is heated, the kinetic energy of that material increases and it’s atoms and molecules move about more. This means that each atom will take up more space due to it’s movement so the material will expand. Some metals expand more than others due to differences in the forces between the atoms / molecules.

When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. The motion and spacing of the particles determines the state of matter of the substance. The end result of increased molecular motion is that the object expands and takes up more space.

Gases

Solids

Gas can be compressed much more easily than a liquid or solid.

potassium metal

Originally Answered: which gas expands the most when thermally heated? The answer is that the gas with the lowest heat capacity at constant pressure, usually given the symbol CsubP .

Water

When air expands, volume occupied by the air/gas increases, the number of molecules or atoms per unit volume decreases, thus the frequency of atomic collisions decrease(no. of times the atoms collide, thus decreasing the pressure). Thus the temperature of the gas decreases as the volume increases.

Heating a gas increases the kinetic energy of the particles, causing the gas to expand. In order to keep the pressure constant, the volume of the container must be increased when a gas is heated.

When gases in containers are heated, their molecules increase in average speed. The gas is therefore under greater pressure when its temperature is higher. This is why fires near sealed gas cylinders are extremely dangerous. If the cylinders heat up enough, their pressure will increase and they will explode.

As a gas (like air) expands, the value of V increases and this has the effect of increasing T (The temperature). As the energy needed to increase it’s temperature must be supplied from somewhere, the gas takes the energy from the surrounding system giving the effect of cooling.

The temperature of a gas is a measure of the speed of its molecules. When the bottle is heated, the air molecules inside start moving faster. These molecules now collide into the balloon with more energy resulting in increased pressure. The increased pressure causes the balloon to expand.

Therefore, at a constant temperature, the kinetic energy will also be the same. Therefore, when gas expands at a constant temperature, pressure decreases as well as kinetic energy of the molecules will remain the same.

As the temperature increases, the average kinetic energy increases as does the velocity of the gas particles hitting the walls of the container. The force exerted by the particles per unit of area on the container is the pressure, so as the temperature increases the pressure must also increase.

Boyond this temperature, there is no distinction between the two phases and a gas cannot be liquefied by compression.

There is no interaction between the molecules. It cannot be converted into a liquid. All molecules of the gas move with the same speed.