A student reacts a pellet of calcium with an excess of dilute sulfuric acid to prepare hydrogen gas.
calcium (s)+sulfuric acid (aq)→calcium sulfate (s)+hydrogen (g) \text{calcium (s)} + \text{sulfuric acid (aq)} \rightarrow \text{calcium sulfate (s)} + \text{hydrogen (g)} calcium (s)+sulfuric acid (aq)→calcium sulfate (s)+hydrogen (g)Although bubbles of hydrogen gas are produced initially, the reaction rapidly slows down and stops, leaving a large portion of the calcium pellet unreacted at the bottom of the flask.
Explain why the reaction stops so quickly, referring to the physical state and properties of the calcium sulfate product.
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.