How we can calculate pressure at different temp, e.g butane at 20 C & it's vapour pressure (absolute pressure) 220 kPa similarly, at 40 C is 360 kPa, at 45C is 385 kPa & 55C is 580 kPa. I want to calculate more pressure values at different temp.
According to Gay-Lussac’s law the pressure of gas is proportional to the absolute temperature upon constant volume. This can be expressed by the equation: P=K×T, where P – the pressure, K – constant, T – the absolute temperature [T = 273 + t(in Co)]. If we need to calculate more pressure values at different temperature, the K parameter should be found: 220 kPa = K(273+20), K = 0.75085, 360 kPa = K(273+40), K = 1.1501, 385 kPa = K(273+45), K = 1.2106, 580 kPa = K(273+55), K = 1.7683 As we can see the K values are different. Calculating its average value we get an equation, which gives the pressure at given temperature: Kav = 1.22