If temperature decreases and the pressure decreases what happens to the volume of a gas?

Answer 1

If a certain number of oxygen (O2) molecules, say 6.022 *1023 of them, are the only thing trapped in a balloon, and you decrease the volume of the balloon, the pressure inside the balloon will increase.

In such a situation, in general, as the volume decreases the pressure increases.

A simple model of an ideal gas has all these gas particles (atoms/molecules) constantly moving around inside the container (e.g., balloon). They move around freely other than when encountering each other or the inside "wall" of the balloon.

In this situation the temperature can be thought of as how fast the molecules are moving (a measurement of their kinetic energy)--the faster they move, the harder they "bump" into each other and the "wall" of the balloon.

The pressure felt on the "wall" of the balloon is a consequence of how many molecules are hitting it (how frequently one "bumps" into it) and how hard they are hitting it.

Since the number of molecules inside the balloon remains constant, the smaller you make the volume inside the balloon, the more often one of the molecules is going to "bump" into the "wall" of the balloon; thereby increasing the pressure.

If you look up Boyle's Law you will find that Robert Boyle determined experimentally that the volume and pressure of a constant amount of gas vary exactly (inversely) with each other. That is, if the amount and temperature of the gas are kept constant, then as the volume decreases, the pressure increases. This makes them inversely proportional: PV = k (where P is Pressure, V is Volume, and k is a constant value).

You'll notice this requires the temperature and amount of gas to remain constant, because if there is more gas there will be more molecules "bumping" or, if the temperature increases, the molecules will have more energy and will be "bumping" harder. To allow for this, the formula becomes the following: PV = k N T (where N is the Number of molecules and T is the Temperature--measured in kelvins).

Answer 2

As volume is reduced pressure goes up. This is a "take off" on the basic gas laws. Take a container of gas, cut its volume in half, and pressure will double (at the same temperature). Volume and pressure are inversely proportional.

Answer 3

V=RT/p so it depends on how much the decrease is:

if both are halved then volume is unchanged!

Answer 4

If all other conditions stay constant, pressure increases.

Answer 5

Pressure Goes Up

Answer 6

The volume decrease.

Answer 7

increases