pH Notes

Identify that water is a weak electrolyte and the self-ionisation of water is represented by Kw. (Formula: Kw = [H+][OH–])

Water: Is a weak electrolyte and the self-ionisation of water is represented by Kw. (Formula: Kw = [H+][OH–])

Apply Kw to calculate the concentration of hydrogen ions from the concentration of hydroxide ions in a solution.

Using Kw to find [H+]: Use Kw=[H+][OH−] to calculate hydrogen‑ion concentration by dividing Kw by the known [OH−].

Calculate pH, hydrogen ion concentration [H+(aq)], pOH and hydroxide ion concentrations [OH–(aq)] for strong acids and bases. (Formula: pH = –log10 [H+] and pOH = –log10[OH–])

Calculating pH, pOH, [H+], and [OH−]: For strong acids/bases, use pH=−log⁡[H+] and pOH=−log⁡[OH−], with [H+][OH−]=Kw to convert between ion concentrations.