text: lab 14.1 laboratory manual. charle's law?   charles's law states that the volume of a given amount of dry ideal gas is directly proportional to the kelvin temperature provided the amount of gas and the pressure remain fixed.  v1 / t1 = v2 / t2  when the three parameters, temperature, volume and pressure are not constant, you can use the relatio p1v1/t1=p2v2/t2 whenever either of the parameters is constant, just cancel it out and you can get the relationship between the remaining variables.