The values of Kw as a function of temperature are as follows: Is the autoionization of water exothermic or endothermic? Choose the right variant. exothermic endothermic it depends on pressure it depends on temperature b What is the pH of pure water at 50°C? 6.631 From a plot of ln(Kw) versus 1/T (using the Kelvin scale), estimate Kw at 37°C, which is the normal physiological temperature.