Credit will be given for strict adherence to the instructions, for observations precisely recorded and for accurate inferences. All tests, observations, and inferences must be clearly entered in your answer book, in ink, at the i.itne time they are made.

C is a sample of copper (II) tetraoxosulphate (VI) crystals. Carry out the following exercises on C. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.

(a) Put half of C in a test tube and heat strongly

(b) Make solution of about 10 cm\(^{-3}\) with the sécond half of C and divide it into three portions

(i) To the first portion, add Sodium hydroxide solution in drops and then in excess. Heat the mixture

(ii) To the second portion, add aqueous ammonia in drops and then in excess followed by few drops of moderately concentrated HCI.

(iii) To the third portion, add all the zinc dust provided and stir thoroughly until there is a visible change.

(a) Suggest how the following liquid reagents can be suitably stored in the laboratory   

(i) X which fumes in moist air; 

(ii) Y which is slowly decomposed by sunlight in ordinary reagent bottles.

(b) State what is observed when aqueous ammonia is added to:

(i) litmus paper;

(ii) Pb(NO\(_3\))\(_2\) solution in drops until in excess

(iii) freshly precipitated AgCI in excess.

(c) A salt sample was suspected to be either Na\(_2\)CO\(_2\) or NaHCO\(_3\). A student who was required to identify it tested a portion for solubility in water and then for effect on litmus paper.

(i) What was observed in each case?

(ii) Give the reason why the student's procedure was unsuitable

(iii) Describe briefly how you would have identified the salt.

All your burette readings (initial and final), as well as the size of your pipette, must be recorded but on no account of experiment procedure is required. All calculations must be done in your answer book.

A is mol dm HCI. B is a solution containing 15.0 g dm of a mixture of NaCl and KHCO\(_3\).

(a) Put A burette and titrate it against 20.0cm\(^3\) or 25.0cm\(^3\) portions of B using methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used. The equation for the reaction involved in the titration is: HCl\(_{aq}\) + KHCO\(_{3(aq)}\) \(\to\) KCl\(_{(aq)}\) +CO\(_{2(g)}\) 

(b) From your results and the information provided above, calculate the:

(i) concentration of KHCO\(_3\), in mol dm\(^{-3}\) in B;

(ii) mass of KHCO\(_3\), in g dm\(^{-3}\) in B

(ii) Percentage by mass of KHCO\(_{3}\) in the mixture, [H=1; C = 12; O = 16; K = 39]

(iv) mass of NaCl in the mixture.

Credit will be given for strict adherence to instructions, for observations precisely recorded, and for accurate inferences. All tests, observations, and inferences must be clearly entered in your answer book, in ink, at the time they are made.

C is one of the following substances; starch or sucrose or glucose D is a simple salt. Carry out the following exercises on C and D. Record your observations and identify any gases evolved.  State the conclusion you draw from the result of each test.

(a)(i) Add about 5 cm\(^3\) of distilled water to a portion of C in a test tube. Stir thoroughly and test with litmus

(ii) Add about 2cm\(^2\) of Fehling's solution to the resulting mixture from (a)(i) above the heat.

(b)(i) Heat a portion of D strongly in a test tube

(ii) Put the rest of D in a boiling tube and add about 10 cm\(^3\) of distilled water. Shake the mixture

(iii) Put about 2 cm\(^3\) of the mixture from (b)(ii)) in a test tube. Add aqueous ammonia in drops and then in excess

(a) If you were provided with anhydrous Na\(_2\)CO\(_3\), spatula and stirrer;

(i) list three other materials you would require to prepare a standard solution of Na\(_2\)CO\(_3\)

(ii) state what you would observe on adding diluted H\(_2\)SO\(_4\) to a portion of the Na\(_2\)CO\(_3\)

(b)(i) Describe briefly one chemical test you would perform to distinguish between zinc ions and aluminium ions in solution.

(ii) Mention one laboratory reagent you would use to;

I. produce ammonia from (NH\(_4\))\(_2\)SO\(_4\)

II. differentiate between precipitates of AgCl and Agl

lll. dehydrate ethanol

(c) Give the reason for each of the following laboratory practices

(i) Aqueous solutions of FeSO\(_4\) are freshly prepared when required for use.

(ii) The first jar of hydrogen collected during its preparation is discarded