Mention one suitable laboratory procedure for

(i) removing carbon (IV) oxide from a sample of air

(ii) determining whether a given sample of water is pure or not;

(iii) concentrating a dilute solution of sodium chloride.

(b) Use the information provided in the table below to outline a suitable procedure for separating a mixture containing P, Q and R into its Components.

(c)(i) Draw a labelled sketch to illustrate the collection of gases by upward displacement of air.

(ii) A gas S, with a rotten egg smell, was evolved when dilute hydrochloric acid was added to T which is a salt of iron (II). S decolorized acidified potassium tetraoxomanganate (VIl) solution and a yellow precipitate V was also obtained. Identify S, T and V.

(iii) State what would be observed on bubbling chlorine through a solution of potassium bromide.

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 and D are samples of two simple salts. Carry out the following exercises on them. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.

(a) Put all of C in a test tube and heat strongly for about 3 to 5 minutes. Allow the residue to cool.

(b) Add about 5cm\(^3\) of distilled water to the residue from (a) above. Shake and test with litmus paper. 

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

A is a solution of tetraoxosulphate (VI) acid. B is a solution containing 1.4g of potassium hydroxide per 250cm\(^3\)

(a) Put A into burette and titrate with 20.0cm\(^3\) or 25.0cm\(^3\) portions of B using methyl orange or screened methyl orange as indicator. Record the volume of your pipette. Tabulate your burette readings and calculate the average volume of A used.

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

(i) concentration of B in mol.dm\(^{-3}\)

(ii) concentration of A in mol dm\(^{-3}\)

(iii) number of hydrogen ions in 1.0dm\(^{-3}\) of A. The equation for the reaction is: H\(_2\)SO\(_4\) + 2KOH \(\to\) K\(-2\)SO\(_4\) + 2H\(_2\)O. [H= 1, O = 16; K = 39. Avogadro constant = 6.0 x 10\(^{23}\)]

(c) State whether the pH of the following would be equal to 7, greater than 7 or less than 7

(i) Solution A:

(ii) Titration mixture of A and B before the endpoint