# how when we increase the temperature pressure also increases.even we know that volume is indirectly proportional to the pressure.so when we increase the temperature volume increase so pressure decreases

Dear student,
There are 3 laws given to setup the relation between Temperature, Pressure, Volume (T, P, V). You should know them to avoid confusion between T, P, V relationship.
1.) Gay-Lussac's law: It states that Pressure is directly proportional to Temperature at constant mass and Volume of gas.
(at constant mass and volume).
2.)  Charle's law:  ; Volume is directly proportional to Temperature at constant mass and Pressure of gas.
3.)  Boyle's law: ; Volume is inversely related to Pressure at constant mass and Temperature of gas.
If we increase the temperature, pressure will also increase as the frequency of collisions of gaseous atoms on the wall of the container increases which increases its pressure. But pressure increases only if Volume is constant (i.e. volume is not been changed at all ) For example-  if we heat a constant mass of a gas contained in a closed vessel, then volume of the gas will be the volume of the vessel, which remains constant on heating. Here on heating pressure will increase.
If a gas is contained in a piston vessel and we are compressing it i.e. reducing its volume the Pressure will increase according to Boyle's law; but here temperature is constant , i.e. no change in temperature.

Regards

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