Will the temperature of a gas increase or decrease or remain the same if the volume is decreased and the pressure is increased?

Answer 1

The volume of a gas will decrease.

Let's think of some good examples. How about an air tank? Its volume is very small but the gas it contains could easily fill a small room. How is the volume so small, then? Because the gas is under extremely high pressure.

Okay so intuition from every day life tells us increase in pressure means decrease in volume.

Examples of temperature? A hot air balloon is filled by a flame that heats the gas inside it. The balloon gets bigger - the volume rises. This is an especially relevant example since the hot air balloon rises due to buoyancy, meaning the air inside it is less dense than the air outside it.

Less dense means there is less mass per volume inside it, so again we know that the gas inside the balloon has undergone an increase in volume in response to being heated.

So increase of temperature means an increase of volume.

The answer to your question, then, is that the volume will decrease (which is actually kinda difficult to do sometimes...but still a theoretical fact).

For further reading and understanding, see "Ideal gas law".

Answer 2

If the pressure is to remain constant then the volume of the gas would increase proportionately with the absolute temperature increase. This is Charles' Law of Constant Pressure: V1 / T1 = V2 / T2.

Answer 3

Imposing either of these stimuli to a gas will increase its volume.

EDIT: The above answer assumes "pressure" to be the pressure on a gas. "Pressure" typically refers to the pressure of a gas. With this in mind, a decrease in pressure would yield a decrease in volume. So, with regards to your question: if the pressure and temperature are decreased and increased by the same factor, the volume will stay the same. If the temperature is increased more than the pressure is decreased, the volume will increase. If the pressure decreases more than the temperature increases, the volume will decrease.

Rather than simply delete the answer above I struck through it so you could see it and I could correct the misconception. The problem with the struck-through answer is that the pressure "of" a gas and the pressure "on" a gas will be in equilibrium and equal so we need not distinguish between the two in answering this question. The original answer by Willblocher is correct.

Answer 4

This can be answered by the ideal gas law(or equation of state) that states:

PV=nRT

P: Pressure

Y: Volume

n: number of molecules

R: gas constant

T: temperature

So in short if temperature increase and pressure is the same, then the volume must increase (provided that no molecules escape)

Answer 5

Boyles's Law leads to:

P V = n R T, where P is pressure, V is volume, R is a physical constant, and T is absolute temperature (in kelvins). n is a constant based on the characteristics of the molecules in the gas.

Thus if T is constant, the right-hand side of the equation remains constant. Therefore if P increases, V must decrease. In practice, what happens if you have a constant amount of gas, and you increase the pressure (i.e. compress it), temperature increases, but even after the temperature returns to the original value, the pressure will be higher.

Note that this doesn't apply if the state of the gas changes -- if the chemical composition or structure changes.

Answer 6

Temperature is directly proportional to both pressure and volume. So, what does this mean for your question? It means... it depends. Decreasing the volume will decrease the temperature, and increasing the pressure will increase the temperature, so it depends on how much the volume and pressure are decreased and increased, respectively. For example:

• If you double the pressure, and cut the volume in half, the temperature will stay the same.
• If you more than double the pressure, and cut the volume in half, the temperature will increase.
• If you less than double the pressure, and cut the volume in half, the temperature will decrease.

Answer 7

The product of (pressure x volume) is proportional to absolute temperature.

So if pressure remains constant, volume alone must be proportional to absolute temperature.

So the volume of the gas in the question must increase when it's heated.

Answer 8

Those two changes produce opposite changes in volume: Volume changes in the

same direction as temperature, but in the opposite direction to pressure. If both

temperature and pressure change, the result could go either way. In order to

calculate the result, we need to know the numbers.

Answer 9

Boyles law requires that the volume increase if temp increases with pressure held constant. PV=nRT See "is Hell exothermic"