Answer when gas changes into liquid?

Answer 1

Matter has four states: Solid, Liquid, Gas, Plasma. When matter changes from state to state depends upon several factors. First the state change point for the atom or molecule varies depending upon physical and chemical makeup. Generally... heavy atoms or molecules need more energy to change states therefore requiring higher temperatures. A second factor effecting state changes is the medium in which the matter is located. If the medium in which the matter is in is heavier then the matter itself, then it will require more energy for the matter to change states. Example: Water at sea level boils at 100C, while heating the water the molecules are pushing against the air molecules, but the water cannot push hard enough to push aside the air molecules and turn into a gas. Once the water has reached 100C it has enough energy to shove air molecules aside and escape into the sky. However, in the mountains water does not have to reach 100C to boil. The air is much thinner so there is less air molecules blocking the water molecule's escape into the sky. Therefore, water molecules don't need to push as hard against the air molecules to turn into a gas. So to change a gas back into a liquid will require the exact opposite. You will have to cool the water vapor lower then 100C before it changes from gas to liquid in the mountains because water molecules move easier in the thin air. At sea level the air is thick and you will not have to cool the water vapor as much for it to change into a liquid. In short, the temperature or energy levels needed to change states depends upon the type of matter and the density of the medium the matter is contained in. You will have to do a little research to find these energy points for a given material. Usually if you find something that says X will boil at Y degrees, is given at 1 atmosphere pressure or the pressure at sea level.

Answer 2

When gas changes into a liquid, a process called condensation occurs. This change happens when the gas loses energy (usually heat) and particles slow down, coming closer together to form a liquid. An example of this is when water vapor in the air cools and turns into liquid water droplets, forming clouds.