2026 CHEMISTRY PRACTICAL, QUESTION 2

All your burette readings (initials and final) as well as the size of your pipette must be recorded but no account of experimental procedure is required. All calculations must be done in your booklet. C and D are inorganic salts. Carry out the following exercises on them. Record your observations and identify any gas(es) evolved. State the conclusions you draw from the result of each test. (a) Put all of C in a test tube and add about 5 cm of distilled water. Shake thoroughly and test the resulting solution with Litmus paper. Divide the solution into three portions. (i) To the first portion, add NaOH(aq) in drops, then in excess. (ii) To the second portion, add NH3(aq) in drops, then in excess. (iii) To the third portion. add AgNO3(aq) followed by HCl(aq) (b)(i) Put all of D in a test tube and add about 5 cm³ of distilled water. Shake thoroughly and feel the test tube. (ii) To about 2 cm³ of the solution, add HCl(aq) QUESTION 2 CHEMISTRY PRACTICAL C and D are inorganic salts. The following observations and conclusions were obtained from the tests carried out. Sample C dissolved in distilled water to form a blue-green solution. The solution turned blue litmus paper red, showing that the solution is acidic. When sodium hydroxide solution was added in drops, a blue precipitate formed. The precipitate remained insoluble in excess sodium hydroxide. This indicates the presence of copper(II) ions. When aqueous ammonia was added in drops, a light blue precipitate formed. The precipitate dissolved in excess ammonia to form a deep blue solution. This confirms copper(II) ions. When silver nitrate solution was added, a white precipitate formed. The precipitate remained insoluble after adding dilute hydrochloric acid, confirming the presence of chloride ions. Therefore, sample C is likely copper(II) chloride. Sample D dissolved in water to form a colourless solution and the test tube felt cold, showing that the dissolution process is endothermic. When dilute hydrochloric acid was added to the solution, effervescence occurred and a colourless, odourless gas was evolved. The gas turned lime water milky, confirming carbon dioxide gas. This indicates the presence of carbonate or hydrogen carbonate ions. SHORTCUTS: - Blue precipitate with NaOH = Cu²⁺ - Deep blue solution in excess NH₃ = Cu²⁺ confirmed - White precipitate with AgNO₃ = Cl⁻ - Bubbling with acid + lime water milky = CO₂ from carbonate A-MOND's TUTORIALS Subscribe for more Chemistry practical shortcuts and explanations. #amondstutorial #science #blackhole