- You are provided with;
- Aqueous hydrochloric acid labeled solution A.
- Solution B containing 8.0 g per litre of sodium carbonate.
- An aqueous solution of substance C labeled solution C
You are required to determine the;
- Concentration of solution A.
- Enthalpy of reaction between hydrochloric acid and substance C
Procedure I
Using a pipette and pipette filler, place 25.0cm3 of solution A into a 250ml, volumetric flask.
Add distilled water to make 250cm3 of solution. Label this solution D.
Place solution D in a burette. Clean the pipette and use it to place 25.0cm3 of solution B into a conical flask. Add 2 drops of methyl orange indicator provided and titrate with solution D. Record your results in table 1. Repeat the titration two more times and complete the table. (4 marks)
Calculate;I II III Final burette reading Initial burette reading Volume of solution D used (cm3) - Average volume of solution D used. (1 mark)
- Concentration of sodium carbonate in solution B.
(Na = 23.0, O = 16.0, C = 12.0) (1 mark) - Concentration of hydrochloric acid in solution D. (2 marks)
- Concentration of hydrochloric acid in solution A. (1 mark)
Using a clean burette, place 2 cm3 of solution A into a boiling tube. Take the initial temperature of the solution in the boiling tube and record it in table 2. Using a clean measuring cylinder, measure 14 cm3 of solution C into 100cm3 beaker and add it to a solution A in the boiling tube. Stir the mixture immediately with a thermometer and record in table 2 the highest temperature reached. Repeat the experiment with the other sets of volumes of A and C in the table and complete it.
(Rinse the thermometer and the boiling tube with distilled water after each experiment) (5 marks)
Volume of solution A (cm3) 2 4 6 8 10 12 14 Volume of solution C (cm3) 14 12 10 8 6 4 2 Initial temperature of solution C (0C) Highest temperature of solution C (0C) Change in temperature ΔT(0C) - On the grid provided, draw a graph of ΔT (vertical axis) against volume of solution A used. (3 marks)
- From the graph, determine;
- The maximum change in temperature. (½ mark)
- The volume of solution A required to completely neutralize solution C. (½ mark)
- Calculate the;
- Number of moles of hydrochloric acid required to completely neutralize solution C. (1 mark)
- Molar enthalpy of reaction between hydrochloric acid and substance C (in kilojoules per mole of hydrochloric acid). Assume the specific heat capacity of the solution is 4.2 Jg-1K-1 and density of solution is 1.0 gcm-3. (2 marks
- You are provided with solid Q. Carry out the following tests on Q and record your observations and inferences in the spaces provided.
- Place a spatula of solid Q into a boiling tube and add 12 cm3 of distilled water.
Shake the mixture thoroughly. Divide the mixture into five portions.
Observations Inferences 1 mark
1 mark
- To the first portion, add 5 cm3 of 2M Nitric (V) acid.
Observations Inferences 1 mark
1 mark
- To the second portion, add four drops of lead (II) nitrate solution.
Observations Inferences 1 mark
1 mark
- To the third portion, add four drops of Barium nitrate solution.
Observations Inferences 1 mark
1 mark
- To the fourth portion, add sodium hydroxide solution dropwise until in excess.
Observations Inferences 1 mark
1 mark
- To the fifth portion, add ammonia solution dropwise until in excess.
Observations Inferences 1 mark
1 mark
- Place a spatula of solid Q into a boiling tube and add 12 cm3 of distilled water.
- You are provided with substance Y.
Carry out the following tests on Y and record your observations and inferences in the spaces provided.- Describe the appearance of solid Y. (1 mark)
- Scoop a little solid Y with a clean metallic spatula and ignite it using non-luminous part of the Bunsen burner flame.
Observations Inferences 1 mark
1 mark
- Add about 10 cm3 of distilled water to the remaining solid Y in a boiling tube.
Divide the resulting mixture into 2 portions.- To the portion one, add 3 drops of acidified potassium manganate (VII) solution.
Observations Inferences 1 mark
1 mark
- To portion two, add sodium hydrogen carbonate.
Observations Inferences 1 mark
1 mark
- To the portion one, add 3 drops of acidified potassium manganate (VII) solution.
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