The table shows experimental data for an experiment involving RR and SS.

1. What is the aim of this experiment? (2 mk)
2. What was the volume of the pipette used? (1 mk)
3. Complete filling the table. (3 mk)
4. Calculate the average volume of the acid used. (3 mk)
5. What were the changes on the litmus papers? (2 mk)
6. Giving reason(s), identify the experiment in which the reaction was: (i) slow (ii) fast. (4 mk)
7. Indicating the state symbols of the reactants and products, write a balanced (i) chemical equation for the reaction between RR and SS. (ii) Write the ionic equation for the reaction. (4 mk)
8. Indicating all the state symbols, write a balanced chemical equation for the neutralization reaction between V1 and V2. (3 mk)
9. How does the concentration of RR affect the time for the mark M to disappear? (3 mk)
10. Write an ionic equation for the reaction. (2 mk)
11. Showing your procedures clearly, calculate the concentration in g/dm^3 of the claimed component (sodium hydroxide). (6 mk)
12. Plot a graph of volume of RR against time. (ii) What can you conclude from the graph? (2 mk)

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You are provided with the following: RR: a solution containing 0.2 M sodium thiosulphate (Na2S2O3); SS: a solution containing 1.0 M hydrochloric acid (HCl); Distilled water; Plain paper marked M; Stopwatch. Procedure (i) Mix 10 cm^3 of solution RR and 50 cm^3 of distilled water in a beaker. (ii) Place the beaker containing the mixture on the paper marked M. (iii) Spread the solution. Wtth the stopwatch and the beaker on the mark M, add 50 cm^3 of solution SS to the beaker. (iv) Switch off the stop watch when the mark M disappears. (v) Record the time taken for the letter M to disappear. (vi) Repeat the experiment using different data as shown in the following table.

1. What is the purpose of the stopwatch in this experiment? (1 mk)
2. Write down the balanced chemical equation for the reaction occurring in the beaker. (3 mk)
3. Identify the precipitate formed in the reaction. (1 mk)
4. Divide the solution obtained in (ii) into three portions. To the first portion, add a few drops of aqueous sodium hydroxide. To the second portion, add a few drops of aqueous ammonia. To the third portion, add a few drops of barium chloride solution followed by dilute hydrochloric acid. (15 mk)
5. Explain why the mark M disappears. (2 mk)
6. If the concentration of HCl was increased, how would it affect the time taken for the mark M to disappear? Explain your answer. (3 mk)
7. Calculate the initial rate of reaction in the first experiment (using the data from the table) in mol dm^-3 s^-1. (5 mk)

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