GESS 3EXP CHEM EYE P2 2023 ANS

8 GESS 3EXP CHEM P2 EYE 2023 TKG A7 The following reaction scheme describes some of the reaction carried out on an unknown mixture. This mixture contains three different salts. (a) Identify the following substances. P: …………………………………………………………………………………. Q: …………………………………………………………………………………. R: …………………………………………………………………………………. S: …………………………………………………………………………………. T: …………………………………………………………………………………. U: …………………………………………………………………………………. [6] (b) Suggest two of the salts that the mixture contains. salt 1: …………………………………………………………………………….. salt 2: …………………………………………………………………………….. [2] [Total: 8]

10 GESS 3EXP CHEM P2 EYE 2023 TKG A9 Wollastonite, CaSiO3, can be produced from the reaction between calcium phosphate and silicon dioxide. 2Ca3(PO4)2 + 6SiO2 → P4O10 + 6CaSiO3 100 g of calcium phosphate, Ca3(PO4)2, was used in this reaction. The actual mass of wollastonite produced was 87 g. Calculate the percentage yield of wollastonite. [4] [Total: 4]

17 GESS 3EXP CHEM P2 EYE 2023 TKG B12 30.0 cm3 of 0.80 mol/dm3 nitric acid was reacted with 10 g of magnesium. (a) Calculate the mass of magnesium nitrate produced. [3] (b) A gas was produced in this reaction. Describe the test and observation to confirm the identity of the gas. …………………………………………………………………………………….. …………………………………………………………………………………….. [1] (c) Suggest a change in observation if nitric acid was replaced with ethanoic acid, CH3COOH, for this reaction. Explain why. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. [2]

18 GESS 3EXP CHEM P2 EYE 2023 TKG (d) Describe the steps to prepare pure and dry magnesium nitrate crystals from nitric acid and magnesium. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. [4] [Total: 10] END OF PAPER

GESS 3EXP CHEM P2 EYE 2023 TKG 11 34 When sulfur is burned, sulfur dioxide is produced. How can the identity of sulfur dioxide be confirmed? test observation A insert a glowing splint into the gas the glowing splint rekindles B use a piece of damp blue litmus paper blue litmus paper turns red and is then bleached C use a piece of damp red litmus paper red litmus paper turns blue and is then bleached