pH of neutral solution

Question

What is the pH of pure water at body temperature of 37 degree Celsius? Kw of water at that temperature is 2.4x10^-14

Answer 1

H₂O <==> H⁺ + OH^-

Kw = 2.4x10^-14 = [H⁺][OH^-]

2.4x10^-14 = [x][x] = x²

x = [H+] = [OH-] = 1.55x10^-7

pH = -log [H⁺] = -log 1.55x10^-7

pH = 6.81