Hey guys. I'm new to the forum :). I'm a high school student who takes physical sciences as one of my subject. The thing is that I've been confused about something I read on chemistry. This might sound stupid but please try and understand that this is confusing me. In the gas laws, Gay Lussac's law states that: " The pressure of a fixed amount of gas at constant volume is proportional to its absolute temperature". Where in Boyle's law it states that: "The volume of a fixed amount of gas is proportional to its pressure at constant temperature". My question is that since the amount of pressure effects the amount of volume, How can the volume be kept at a constant when the temperature causes a change in pressure ( which in turn effects volume)? Also why is a direct relationship expressed as P/T and an inverse relationship expressed as PV=PV?