What is the mathematical relationship between pressure and temperature?

I think you mean Gay-Lussac's law

P1/T1=P2/T2

provided the volume remains constant.

The mathematical relationship between pressure and temperature is described by the gas law equation. More specifically, it is defined by the ideal gas law equation, which is:

PV = nRT

Where:
P is the pressure of the gas
V is the volume of the gas
n is the number of moles of gas
R is the ideal gas constant
T is the absolute temperature of the gas

To understand the relationship between pressure (P) and temperature (T) in this equation, we can consider the other variables constant and focus on P and T only. Rearranging the equation, we get:

P = (nRT) / V

From this equation, we can see that pressure (P) is directly proportional to temperature (T) when the other variables (n, R, and V) are held constant. In other words, if we increase the temperature of a gas while keeping the number of moles, volume, and the ideal gas constant constant, the pressure will also increase. Similarly, if we decrease the temperature, the pressure will decrease. This relationship follows Charles's Law, which states that the volume of a gas is directly proportional to its absolute temperature at constant pressure.

It's important to note that this relationship holds true for ideal gases under ideal conditions. Real gases may deviate slightly from these ideal gas laws under certain circumstances.