Determine an unknown univalent element in a carbonate. You are Provided with the following solutions: (i) P: containing 2.65 g of the univalent element carbonate (X₂CO₃) dissolved in a 250 cm³ of an aqueous solution. (ii) H: containing 12.6 g of nitric acid dissolved in a litre of an aqueous solution. Procedure: Titrate nitric acid from the burette against carbonate solution using two drops of methyl orange indicator and record the end point. Repeat the procedure to obtain three burette readings and tabulate the results.

1. Calculate the average titre volume. (2 mk)
2. Calculate the average titre volume. (1 mk)
3. Find the volume of the acid which was required to complete neutralization. (1 mk)
4. Find the volume of the acid which was required to complete neutralization. (1 mk)
5. Write balanced chemical equation for the reaction. (2 mk)
6. Write balanced chemical equation for the reaction. (1 mk)
7. Calculate the molarities of the acid and base. (4 mk)
8. Calculate the molarities of the acid and base. (1 mk)
9. Determine the molar mass of the univalent element carbonate and name of the univalent element. (1 mk)
10. Determine the molar mass of the univalent element carbonate and name of the univalent element. (4 mk)
11. Write the chemical formula of the univalent element carbonate. (1 mk)
12. Write the chemical formula of the univalent element carbonate. (1 mk)

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Study the reaction between sodium thiosulphate and hydrochloric acid at different temperatures. The chemicals provided are labelled as A₁ for 0.05 M sodium thiosulphate and A₂ for 1.0 M hydrochloric. Also, you are provided with a piece of white paper marked X on which a 100 cm³ beaker containing the reaction mixture to be placed during the experiment. Measure 30 cm³ of A₂ and put it into the 100 cm³ beaker place on top of the X marked on the piece of paper. Then, measure 30 cm³ of A₁, put it into boiling tube, insert a thermometer into it and heat on water bath until it reaches a temperature of 40°C. The next step, transfer the heated solution A₁ into the beaker containing solution A₂ and immediately starting the stop watch. This step is followed by swirling the mixture, (while observing from above) and recording the time taken for letter X to disappear completely. Repeat the procedure by varying the temperature as shown in the table. Table: Experimental Data Volume of Volume of A₂ Temperature of A₁ Time (s) A₁ (cm³) (cm³) (oC) 30 30 40 30 30 50 30 30 60 30 30 70 30 30 80

1. Complete filling the table. (5 mk)
2. (i) Plot a graph of volume N (vertical axis) against time (horizontal axis) taken for the letter X to disappear completely. (ii) State what does the shape of the graph indicate. (4 mk)
3. Give reason why did the letter X disappear. (2 mk)
4. Write the electronic configuration of the product which causes the solution to be cloudy (milky). (2 mk)
5. Write the ionic equation for the reaction between N and N. (3 mk)
6. Plot a graph of volume of A₁ against the rate of the reaction. (2 mk)
7. State why N was added to N . (2 mk)

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