Determine water of crystallization in sodium carbonate. You are provided with the following solutions: K: 1.825 g of hydrochloric acid in a 0.50 dm3 solution. L: 3.575 g of pure hydrated sodium carbonate (Na2CO3.XH2O) in a 0.25 dm3 of solution. Titrate the acid (in the burette) against the alkali (in the conical flask) using methyl orange (MO) indicator. Next they had to repeat the procedure to obtain three more titre values and record the results in a tabular form. (a) What was the volume of pipette used? (b) What was the colour change at the end point of titration? (c) Calculate the average volume of the acid used. (d) Showing your procedure clearly, determine the value of X (the number of molecules of water of crystallization) in the formula (Na2CO3.XH2O).

1. What was the volume of pipette used? (0 mk)
2. What was the colour change at the end point of titration? (0 mk)
3. Calculate the average volume of the acid used. (0 mk)
4. Showing your procedure clearly, determine the value of X (the number of molecules of water of crystallization) in the formula (Na2CO3.XH2O). (0 mk)

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Determine the effect of concentration on the rate of chemical reaction. The chemicals provided are labelled as W containing 79.0 g of sodium thiosulphate in 0.5 litre of solution and V containing 6.3 g/dm3 nitric acid solution. You are also provided with a stopwatch and a piece of white paper marked X on which a 50 cm3 beaker containing the reaction mixture. Proceed as follows: (i) Place a 50 cm3 beaker on top of letter X in such a way that the letter X is visible when viewed from above. (ii) Using measuring cylinder, measure 2 cm3 of solution W and pour it into a 50 cm3 beaker. Add 3 cm3 of distilled water. (iii) Measure 5 cm3 of solution V and put it into a 50 cm3 beaker containing solution W and distilled water and immediately start a stopwatch. (iv) Swirl the contents in the 50 cm3 beaker and stop the stopwatch when the letter X disappears. (v) Record the time for letter X to disappear. (vi) Repeat the experiment by varying the volume of W and distilled water as shown in the following table of experimental data. Table: Experimental Data Time taken for Volume of Volume of Volume of the letter X to Experiment Distilled W (cm3) V (cm3) disappear in water (cm3) sec. (i) 2 5 3 (ii) 3 5 2 (iii) 4 5 1 (iv) 5 5 0

1. Place a 50 cm³ beaker on top of letter X in such a way that the letter X is visible when viewed from above. (0 mk)
2. Complete the table by filling the empty column. (0 mk)
3. Using measuring cylinder, measure 2 cm³ of solution W and pour it into a 50 cm³ beaker. Add 3 cm³ of distilled water. (0 mk)
4. Write a balanced chemical equation for the reaction between sodium thiosulphate and nitric acid. (0 mk)
5. Measure 5 cm³ of solution V and put it into a 50 cm³ beaker containing solution W and distilled water and immediately start a stopwatch. (0 mk)
6. What substance caused the letter X to disappear in experiment? (0 mk)
7. Swirl the contents in the 50 cm³ beaker and stop the stopwatch when (25 mk)
8. Plot a graph of the volume of Na2S2O3 (cm3), y-axis against time (s), x-axis. (0 mk)
9. What conclusion can you draw from the graph regarding the disappearance of the letter X? (0 mk)

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