What does a solution with higher pH level indicate?

1 Answer
Feb 7, 2017

An alkaline solution.

Explanation:

We interrogate the auto-protolysis equilibrium:

2H_2O rightleftharpoonsHO^(- )+ H_3O^+

See this old answer. In water, this equilibrium has been carefully measured, such that K_w=[H_3O^+][HO^-]=10^(-14) at 298K.

We classify the acidity of the solution on the pH scale, where pH=-log_10[H_3O^+]. Given the negative function, numerically higher pH values indicate that [HO^-] is greater than 10^-7 mol*L^-1, and, necessarily, [H_3O^+] is LESS than 10^-7 mol*L^-1.