SASS Chem Data of Ionic Cmpds Summary

Page 1 ST ANDREW’S SECONDARY SCHOOL NAME CLASS CHEMISTRY 6092 Chemical Data of Common Ionic Compounds: A Summary Solubility, colour, chemical analysis General advice • It is essential that you follow the instructions and read the information carefully before you carry out the experiment(s). Apart from testing of gases, you should not use additional reagents for any test in the experiment. • Amount to use: • Reagents selected for use in tests must be included in your answers with their full chemical name/ correct formulae. E.g: Dilute hydrochloric acid : HCl (aq) [NOT H+ / dilute acid] Dilute silver nitrate solution : AgNO3 (aq) [NOT Ag+ / nitrate solution / Ag2NO3] • Check for contradictions within your answers. E.g: When recording the observation for Zn2+ in excess NaOH (aq): “White insoluble precipitate dissolves” does not make sense! You should record it as: “White precipitate formed at first, soluble in excess NaOH (aq) forming a colourless solution” • When you are asked to test the pH, you should give the pH number and NOT acidic / alkaline. pH is determined using Universal Indicator; litmus paper can only determine if it is acidic / alkaline. E.g: Turns blue litmus paper red = the solution is acidic Blue litmus paper remains unchanged = the solution is NOT acidic (either alkaline or neutral) • When heating a solid, heat gently first then strongly. When heating a liquid or solution, move the test tube in and out of the flame every now and then. Skills Build-up These are some important skills in Chemistry: Manipulation and Observation • Demonstrating experimental techniques and skills • Making observations and recording readings or measurements • Presenting data Analysis • Processing data • Drawing conclusions Planning • Planning an investigation • Producing a procedure for an investigation • Evaluating the plan and procedure (after carrying out the plan) The next few sections list some guidelines for you to follow when carrying out Chemistry experiments. 1 Manipulation and Observation 1.1 Demonstrating Experimental Techniques and Skills A Set up an apparatus from a diagram or from written instructions. B Follow a sequence of instructions to perform an experiment. C Use clean apparatus when doing experiments. D Use the appropriate amount of chemicals. Unless otherwise specifi ed, • use suffi cient amount of the solid to fi ll about 1 cm depth of a test tube (Figure 1); • add liquids or solutions to a depth of about 2 cm in a test tube (Figure 2) or about one-third height in a boiling tube (Figure 3). Figure 3 Boiling tube with liquid Figure 1 Test tube with solid Figure 2 Test tube with liquid 1–3 of boiling tube liquid solid1 cm { 2 cm liquid © 2013 Marshall Cavendish International (Singapore) Private Limited 1Skills Build-up (S)CMPB_Skills-Buildup.indd 1(S)CMPB_Skills-Buildup.indd 1 8/2