States of Matter. They are of course; solid, liquid and gas. It is important to remember that heat must be added to a substance to make it change state from solid to liquid and from liquid to a gas. It is just as important to note that heat must be removed from a substance to make it change state from a gas to a liquid and from a liquid to a solid.
When a sufficient amount of heat is absorbed by a solid it passes into the liquid state, like melting ice. On absorbing more heat the liquid evaporates and changes to a gas, (like water boiling to steam).
- Change of state = Energy (Heat) Transfer
- Cooling = absorbing heat energy (Solid > Liquid > Gas) = evaporation
- Heating = rejecting heat energy (Gas > Liquid > Solid) = condensation
The dry ice is much colder than the warm water. By absorbing heat from the warm water, the dry ice changes state from solid to gas (evaporation)
On top of the warm water is a layer of water vapour. This cold gas, bubbles up, and cools down the water vapour, turning it into fog (condensation).
Substances can change state, usually when they are heated or cooled. For example, liquid water turns into steam when it is heated enough, and it turns into ice when it is cooled enough. State changes are reversible – ice can be melted and then frozen again. No new elements or compounds are formed. The closeness, arrangement and motion of the particles in a substance change when it changes state.
The green arrow ‘increasing internal energy’ is HEAT being absorbed (and creating a cooling effect).