2025 Montfort Sec 6092 Revision Guide for Practical

6092 Practical Revision Guide Chemistry Practical Test Candidates may be asked to carry out exercises based on: 1. Titration, e.g. acid-base titration (with suitable indicators such as methyl orange, screened methyl orange, and thymolphthalein). Other types of titrations may also be required, and where appropriate, sufficient working details will be given. 2. Speeds of reaction that may involve measuring of quantities, e.g. temperature, volume, length, mass or time measurements 3. Experiments involving separation techniques such as paper chromatography, filtration and distillation 4. Salt preparation 5. Gas collection Candidates would not be required to carry out drying of gases during practical examination. 6. Qualitative inorganic analysis involving an element, a compound or a mixture, including displacement reactions and tests for oxidising and reducing agents. Candidates should be familiar with the reactions of cations, reactions of anions and tests for gases as detailed in the Notes for Qualitative Analysis. Candidates would not be required to carry out tests involving sulfur dioxide gas. Reactions involving ions not included in the Notes for Qualitative Analysis may be tested: in such cases, candidates will not be expected to identify the ions but only to draw conclusions of a general nature. Candidates should not attempt tests, other than those specified, on substances, except when it is appropriate to test for a gas. 7. Qualitative organic analysis requiring a knowledge of simple organic reactions as outlined in Topic 11 Organic Chemistry, e.g. test-tube reactions indicating the presence of unsaturation (C=C) may be set, but this would be for the testing of observation skills and drawing general conclusions only.

Practical Techniques a) Candidates should normally record burette readings to the nearest 0.05 cm3 and they should ensure that they have carried out a sufficient number of titrations, e.g. in an experiment with a good end-point, two titres within 0.20 cm3. b) In qualitative analysis, candidates should use approximately 1 cm depth of a solution (1– 2 cm3) for each test and add reagents slowly, ensuring good mixing, until no further change is seen. Candidates should indicate at what stage a change occurs. Answers should include details of colour changes and precipitates formed, and the name and test for any gases evolved.

Tips on Qualitative Analysis A. Procedures for Heating 1. Keep the air hole closed when lighting a Bunsen burner. 2. When the Bunsen burner is lighted, open the air hole a little. 3. Use a test tube holder when heating anything in a test tube. 4. Slant the test tube. 5. Point the mouth of the test tube away from yourself and anyone nearby. 6. While heating, remove the test tube from the flame every now and then and shake the tube gently. (to prevent the solution from splurting out) 7. Ensure that the test tube is dry if you ar