Tutorial

In this problem we are given pH and asked to solve for the hydrogen ion concentration. Using the equation, pH = − log [H⁺] , we can solve for [H⁺] as,

− pH = log [H⁺] ,

[H⁺] = 10^−pH,

by exponentiating both sides with base 10 to "undo" the common logarithm. The hydrogen ion concentration of "Solution A" is,

[H⁺] = 10^−5.6 ≈ 0.0000025 = 2.51 × 10⁻⁶ M.

We can always check our solution by computing −log (2.5 × 10⁻⁶) ≈ 5.6.