A student wants to measure the pH of a dark purple blackcurrant juice.
Why is a pH meter better than universal indicator paper for this juice?
The indicator paper only shows whether the juice is acidic or alkaline.
The indicator paper reacts with the juice and changes its pH.
The colour of the juice makes the indicator colour hard to see.
The pH meter does not need to be calibrated before use.
53 exam-style questions on OCR GCSE Chemistry 3.3 Types of chemical reactions, covering 3.3.1 Oxidation and reduction in terms of oxygen, 3.3.2 Acids, alkalis and neutralisation, 3.3.3 The pH scale and measuring pH, 3.3.4 Oxidation and reduction in terms of electrons, 3.3.5 Dilute and concentrated, weak and strong acids, and 3.3.6 Hydrogen ion concentration and pH. Each one has a worked solution and a mark scheme showing where the marks go.