Chemistry 0620/62 October/November 2022: question paper and mark scheme

Question

A mixture of three coloured compounds was separated using the apparatus shown in the diagram. lid paper A baseline (a) Give the name of the item of apparatus labelled A. . …… [1] (b) One drop of the mixture of coloured compounds was placed on the paper and some solvent was poured into A. Draw on the diagram: ● a spot (●) to show where the drop of the mixture of coloured compounds should be placed on the paper at the start of the experiment ● a line to show the level of the solvent in A at the start of the experiment. [2] (c) Name an item of apparatus that should be used to place a drop of the mixture of coloured compounds onto the paper. . …… [1] (d) State when the paper should be removed from the solvent in A. . …… [1] (e) Name this method of separation of coloured compounds. . …… [1] [Total: 6]

Question

A student investigated the temperature change when two different aqueous solutions of sodium hydroxide, solution G and solution H, reacted with dilute hydrochloric acid. Two experiments were done. (a) Experiment 1 ● A burette was rinsed with distilled water and then with dilute hydrochloric acid. ● The burette was filled with the dilute hydrochloric acid. The hydrochloric acid was then run out through the tap until the level was on the 0.00 cm3 mark. ● A 50 cm3 measuring cylinder was used to pour 20 cm3 of solution G into a beaker. ● A thermometer was used to measure the initial temperature of solution G. ● 5 cm3 of dilute hydrochloric acid was added from the burette into the beaker. ● The mixture in the beaker was stirred using the thermometer and the temperature of the mixture was measured. ● Another 5 cm3 of dilute hydrochloric acid was added from the burette into the beaker. ● The mixture in the beaker was stirred using the thermometer and the temperature of the mixture was measured. ● 5 cm3 portions of dilute hydrochloric acid continued to be added and the temperature measured until a total of 35 cm3 of dilute hydrochloric acid had been added. Experiment 2 ● Experiment 1 was repeated using solution H instead of solution G. Use the thermometer diagrams to complete the table. Experiment 1 using solution G Experiment 2 using solution H total volume temperature temperature of dilute thermometer temperature thermometer temperature change change hydrochloric diagram / C diagram / C since start since start acid added / C / C / cm3 30 30 0 25 25 20 20 30 30 5 25 25 20 20 30 30 10 25 25 20 20 30 30 15 25 25 20 20 30 30 20 25 25 20 20 30 30 25 25 25 20 20 30 30 30 25 25 20 20 30 30 35 25 25 20 20 [5] (b) Complete a suitable scale on the y-axis and plot the results from Experiments 1 and 2 on the grid. Draw two smooth line graphs. Both curves must start at (0,0). Clearly label your lines. temperature change / C 0 0 5 10 15 20 25 30 35 total volume of dilute hydrochloric acid added / cm3 [5] (c) From your graph, deduce the temperature change obtained when a total volume of 13 cm3 of dilute hydrochloric acid is added in Experiment 1. Show clearly on the grid how you worked out your answer. temperature change = …… °C [2] (d) Explain why the temperature change decreases towards the end of each experiment. . …… . …… [1] (e) Explain what conclusion about the concentrations of solution G and solution H can be made from the results of Experiments 1 and 2. . …… . …… . …… . …… [2] (f) Explain how the results obtained would be different if a polystyrene cup is used instead of the beaker. . …… . …… . …… . …… [2] (g) Give an advantage and a disadvantage of using a burette rather than a measuring cylinder to add the dilute hydrochloric acid to solution G and solution H. advantage . …… . …… disadvantage …… . …… [2] [Total: 19]

Question

Solid I and solid J were analysed. Tests were done on each substance. tests on solid I tests observations test 1 Dilute hydrochloric acid was added to a effervescence was seen, the solid dissolved boiling tube containing solid I. to form a colourless solution Any gas produced was tested. the gas turned limewater milky test 2 A flame test was carried out on the solution a red flame was seen formed in test 1. (a) Identify the gas made in test 1. . …… [1] (b) Identify solid I. . …… . …… [2] tests on solid J Solid J was aluminium chloride. Solid J was dissolved in water to form solution J. Solution J was divided into four approximately equal portions in four test-tubes. (c) Aqueous sodium hydroxide was added dropwise and then in excess to the first portion of solution J. observations …… . …… [2] (d) Aqueous ammonia was added dropwise and then in excess to the second portion of solution J. observations …… . …… [2] (e) About 1 cm depth of dilute nitric acid followed by a few drops of aqueous barium nitrate were added to the third portion of solution J. observations …… [1] (f) About 1 cm depth of dilute nitric acid followed by a few drops of aqueous silver nitrate were added to the fourth portion of solution J. observations …… [1] [Total: 9]

Question

Hydrogels are powders that absorb water to form hydrated solids. Hydrogels and the hydrated solids formed are insoluble in water. Plan an investigation to find which hydrogel, hydrogel A or hydrogel B, is able to absorb the greater mass of water. You are provided with samples of hydrogel A, hydrogel B, water and common laboratory apparatus. . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… . …… [6]