The universal gas law, pv = nrt, describes the relationship among the pressure, volume, and temperature of a gas. p = pressure v = volume t = temperature (kelvin) n = number of moles (quantity of gas particles) r = universal gas constant at a constant temperature of 1 k, the pressure and volume of 1 mole of gas vary inversely. use the values in the table to find the value of r. volume (liters): 4.155, 16.62, 33.24. pressure: 2, 0.5, 0.25