DSEE Chemistry Paper 2C 2022 — Past Paper & Online Quiz

1. 0 marks

Thermometer 100 cm3 plastic beaker Perform the experiment through the given procedure and then answer the questions that follow. Procedure: (i) Measure 50 cm3 of distilled water and transfer it into a plastic beaker. (ii) Insert a thermometer into the distilled water in the plastic beaker and record the temperature of the water. (iii) Add D1 into the beaker containing distilled water and immediately start a stopwatch while stiring gently with your thermometer to dissolve the salt. (iv) Record the temperature of the solution after every 30 seconds for four (4) minutes. (v) Repeat steps (i) to (iv) except that instead of D1 in step (iii) use D2.

(a) Present the results in a tabular form. 0 mk

((a)(i) Present your results in an appropriate tabular form. 3 mk

(b) Calculate the heat of solution for 2 g of each salt in water (assume that no heat is lost to the surroundings). 0 mk

(c) State whether the process of dissolving salt D1 or D2 is endothermic or exothermic. Give one reason to support your answer. 0 mk

(d) Why it is not advised to hold the pipette from its bulb? 1 mk

(e) What is the colour change of the indicator for the reaction between sodium hydroxide and oxalic acid. 1 mk

(f) Calculate the concentration of solution TT in mol dm3 . 3 mk

(g) Calculate the concentration of PP in mol dm3 . 5 mk

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3. 0 marks

Perform a systematic qualitative analysis experiment to identify the cation and the anion present in the sample Q. Base your experiment on the listed tests and then answer the questions that follow: (i) Appearance of sample Q. (ii) Action of heat on sample Q in a test tube. (iii) Action of dilute sulphuric acid on the solid sample. (iv) Action of concentrated sulphuric acid on the solid sample. (v) Flame test. (vi) Solubility of the sample.

(i) Appearance of sample Q. 1 mk

(ii) Action of heat on sample Q in a test tube. 2 mk

(iii) Action of dilute sulphuric acid on the solid sample. 2 mk

(iv) Action of concentrated sulphuric acid on the solid sample. 2 mk

(v) Flame test. 2 mk

(vi) Solubility of the sample. 1 mk

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2. 0 marks

Perform a systematic qualitative analysis experiment to identify the cation and the anion present in the sample Q. Base your experiment on the listed tests and then answer the questions that follow: (i) Appearance of sample Q. (ii) Action of heat on sample Q in a test tube. (iii) Action of dilute sulphuric acid on the solid sample. (iv) Action of concentrated sulphuric acid on the solid sample. (v) Flame test. (vi) Solubility of the sample. (vii) Confirmatory test for the anion. (viii) Confirmatory test for the cation.

(a) Prepare a relevant Table showing the qualitative analysis results. 0 mk

(none) Describe the procedure you would follow to investigate the heat of reaction of each salt when dissolved in water. You should include: (a) How to measure the temperature change. (b) How to ensure accuracy in your measurements. (c) How to present your findings. (d) Outline one (1) possible source of error in this experiment and how to minimize it. 15 mk

(b) What are the cation and anion present in the sample? 0 mk

(c) Write the reaction equation to indicate what took place in test (iv). 0 mk

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Chemistry · Paper 2C · 2022

Chemistry · Paper 2C · 2022

Section A

Section B

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