IB Chemistry - Acids and Bases

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The acidity of a solution is dependent on the concentration of hydrogen ions. The pH scale measures this acidity.

Syllabus reference

Reactivity 3.1.4 - The pH scale can be used to describe the [H+] of a solution:

  • pH = –log10[H+]; [H+] = 10–pH
  • Perform calculations involving the logarithmic relationship between pH and [H+].


  • Include the estimation of pH using universal indicator, and the precise measurement of pH using a pH meter/probe.
  • The equations for pH are given in the data booklet.

Tools and links

  • Tool 1, Tool 2, Tool 3 - What is the shape of a sketch graph of pH against [H+]?
  • Nature of science, Tool 2 - When are digital sensors (e.g. pH probes) more suitable than analogue methods (e.g. pH paper/solution)?

In Chapter 8.3