Copy of MGS Chemistry P3 (Q3)

Page 8 of 11 Methodist Girls’ School Chemistry Paper 3 Sec 4 Preliminary Examination 2024 Class Index Number Name : __________________________________________ 3 Read all the instructions carefully before starting the experiments in Question 3. (a) You are provided with two samples of R and a sample of solution S. Carry out the following tests and record your observations in the table. You should test and name any gas evolved. Test No. Test Observations 1 Remove the stopper from a sample of R in a test -tube. Heat the solid in the test - tube gently at first and then strongly. Leave it to cool. You do not need to test for any gas evolved. 2 Transfer the other provided sample of solid R to a boiling tube. Carefully add hydrochloric acid to a depth of approximately 5 cm. Test any gases given off. Keep this solution for Test 3 and 4. 3 Add 1 cm depth of the solution from Test 2 into a test -tube. Add aqueous sodium hydroxide slowly with shaking until no further change is seen. 4 Add 1 cm depth of the solution from Test 2 into a test-tube. Add aqueous ammonia slowly with shaking until no further change is seen. 5 To 1 cm depth of S in a test -tube, add aqueous sodium hydroxide until no further change is seen. Allow the final mixture to stand for a few minutes.

Page 9 of 11 Methodist Girls’ School Chemistry Paper 3 Sec 4 Preliminary Examination 2024 6 (a) To 1 cm depth of S in a test-tube, add an equal volume of aqueous hydrogen peroxide. (b) Pour the mixture from ( a) into a boiling tube and then add aqueous sodium hydroxide. 7 (a) To 1 cm depth of S in a test-tube, add an equal volume of aqueous barium nitrate. (b) Add dilute nitric acid to the mixture from (a). 8 To 1 cm depth of acidified potassium manganate (VII) in test-tube, add an equal volume of S. [12] (b) State the formula of solid R. [1] (c) Deduce the role of S in Test 8. Use your observations to explain how you have reached this conclusion. [2] [Total: 15]

Page 10 of 11 Methodist Girls’ School Chemistry Paper 3 Sec 4 Preliminary Examination 2024

Page 11 of 11 Methodist Girls’ School Chemistry Paper 3 Sec 4 Preliminary Examination 2024 QUALITATIVE ANALYSIS NOTES Test for anions anion test test result carbonate (CO32-) add dilute acid effervescence, carbon dioxide produced chloride (Cl-) [in solution] acidify with dilute nitric acid, then add aqueous silver nitrate white ppt. iodide (I-) [in solution] acidify with dilute nitric acid, then add aqueous silver nitrate yellow ppt. nitrate (NO3-) [in solution] add aqueous sodium hydroxide, then aluminium foil; warm carefully ammonia produced sulfate (SO42-) [in solution] acidify with dilute nitric acid, then add aqueous barium nitrate white ppt. Test for aqueous cations cation effect of aqueous sodium hydroxide effect of aqueous ammonia aluminium (Al3+) white ppt., soluble in excess giving a colourless solution white ppt., insoluble in excess ammonium (NH4+) ammonia produced on warming - calcium (Ca2+) white ppt., insoluble in excess no ppt. copper(II) (Cu2+) light blue ppt., insoluble in excess light blue ppt., soluble in excess giving a dark blue solution iron(II) (Fe2+) green ppt., insoluble in excess green ppt., insoluble in excess iron(III) (Fe3+) red-brown ppt., insoluble in excess red-brown ppt., insoluble in excess zinc (Zn2+) white ppt., soluble in excess giving a colourless solution white ppt., soluble in excess giving a colourless solution Test for gases gas test and test result ammonia (NH3) turns damp red litmus paper blue carbon dioxide (CO2) gives white ppt. with limewater (ppt. dissolves with excess CO2) chlorine (Cl2) bleaches damp litmus paper hydrogen (H2) “pops” with a lighted splint oxygen (O2) relights a glowing splint sulfur dioxide (SO2) turns aqueous acidified potassium manganate(VII) from purple to colourless