What is pH value of water at 27 degree C?

Answer 1

The self-ionisation constant Kw of pure water at 27oC is 1.26E-14 (or 1.26.10-14)

Because it is neutral, the hydronium ion concentration [H3O+] and the hydroxide ion concentration [OH-] are equal to each other, and are therefore equal to the square root of Kw: (and some calculus has to be done:)

Kw= [H3O+].[OH-] = (x).(x) = x2 = 1.26.10-14 ---> x = SQRT(1.26.10-14) = (1.26.10-14)1/2

The equation for pH = -log[H3O+] = -log{x} , so

for water at 27oC: pH = -log{(1.26.10-14)1/2} = 1/2*[-log(1.26.10-14)] = 1/2*13.9 = 6.95

pH = 6.95 at 27 oC

Answer 2

The pH of pure water at 27 degrees Celsius is approximately 7, which is considered neutral. However, this value can vary slightly due to dissolved gases and impurities in the water.