Unit 5.4: pH scale and pH calculations

Learning Objectives

• Explain the pH scale as a scale of numbers from 0 to 14 used to express the acidity or alkalinity of a solution.
• Calculate pH values of strong acids and strong bases.
• Define the concept of K_w as the equilibrium constant for the ionisation of water – the ionic product of water (ionisation constant of water).
• Explain the auto-ionisation of water i.e. the reaction of water with itself to form H₃O⁺ ions and OH^–