Dilute nitric acid reacts with solid sodium carbonate powder. Sodium carbonate is a weak base.
A student investigates how the pH changes as sodium carbonate is added to dilute nitric acid.
Here is the method used:
Step 1: Use a volumetric pipette to transfer 25.0 cm3 of dilute nitric acid into a glass beaker. Step 2: Measure and record the pH of the acid using a calibrated pH probe. Step 3: Add a 0.2 g portion of sodium carbonate powder and stir the mixture thoroughly. Step 4: Measure and record the pH. Step 5: Repeat Steps 3 and 4 until there is no further change in the pH.
Give one safety precaution that the student should take during this experiment.
276 exam-style questions on Edexcel GCSE Chemistry 4.1 Acids, covering 4.1.1 Acids, alkalis and the pH scale, 4.1.2 Hydrogen ion concentration and pH, 4.1.3 Dilute and concentrated, weak and strong acids, 4.1.4 Bases, alkalis and the reactions of acids, 4.1.5 Chemical tests for hydrogen and carbon dioxide, 4.1.6 Neutralisation as a reaction of acids with bases, 4.1.7 Preparing soluble salts, and 4.1.8 Solubility rules and preparing insoluble salts. Each one has a worked solution and a mark scheme showing where the marks go.