Why would decreasing the temperature of a gas in a syringe make the volume decrease?


Why would decreasing the temperature of a gas in a syringe make the volume decrease?

In: Chemistry

Temperature is just a measure of the average kinetic energy (motion) of the molecules in a gas. If you decrease the temperature, that means they’re moving slower.

If they’re moving slower, then they’re running into the walls of the syringe less often AND slower. This means they’re pushing less hard on the sides of the syringe. The outside air pressure is still pushing in equally hard, but the inside gas pushing out is less, so the outside air wins, and pushes inward. This is the volume decreasing.

Heat = excited particles bouncing faster all over the place adding pressure

Colder = less excited particles so less pressure

I’m not entirely sure that volume decrease is the correct term though, maybe someone else can help

Gasses are matter whose atoms are constantly bouncing around like they’re on crack. If a gas is hotter the atoms have more energy, bounce around faster, which causes the gas itself to expand (become less dense).

If energy is removed, the gas cools, the atoms bounce slower, and the density increases.

Because heat is the molecules moving around more energetically, exerting more force on each other and the walls of the cylinder.

Envision your living room with twenty elderly people sleeping in chairs or having a quiet chat over the table. Each of them represent a gas molecule at low temperature.

Now replace them with twenty sugared-up six year olds running wild at a birthday party for heat. The number of molecules are the same, but the latter situation leaves a lot more dents in your walls.

The difference between a solid, liquid and gas comes down to the amount of space between the atoms. Atoms are kind of like tiny little balls, and everything is made of them. There’s a lot of different kinds of atoms, but I won’t go into that since it’s not really important for your question.

Gases have a lot of space between the atoms, and a side-effect of this is that the atoms can move around easily. Warming up a gas causes those atoms to move around a whole lot faster, and this movement causes them to push each other away even further and they spread out and increase their “volume”. Cooling a gas down has the opposite effect of slowing down the atoms so they don’t push away so much and the space between them gets smaller, reducing the total “volume”.

Cooling a gas enough can turn it into a liquid, which really just means the atoms are close enough together to be really dense, but still have enough space between them to slip and slide around easily so they “flow” around each other. Solids are just atoms that are so tight together that they can hardly move at all.