Question

What does a solution with higher pH level indicate?

Answer 1

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`.