A is a solution containing 0.050 mol. dm of tetraoxosulphate (VI) acid. B is a solution of anhydrous trioxocarbonate (IV).

(a) Put A into the burette and titrate with 20cm\(^3\) or 25cm\(^3\) portions of B using methyl orange as an 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 solution B in mol. dm\(^{-3}\)

(ii) mass of sodium tetraoxosulphate (VI) that would be formed in solution of 1dm\(^3\) of solution B were neutralized by solution A

(iii) volume of carbon (IV) oxide at s.t.p. that would be liberated in (b)(ii) above. The equation for the reaction is: N\(_2\)CO\(_{3(aq)}\) + H\(_2\)SO\(_{4(aq)}\) \(\to\)  Na\(_2\)SO\(_{4(aq)}\) + H\(_2\)O\(_{(l)}\) + CO\(_{2(g)}\) [O = 16; Na = 23, S = 32; molar volume of gases of s.t.p. = 22.4dm\(^3\) 

(a) State;

(i) One advantage:

(ii) One disadvantage of evaporation of salt solutions to dryness over crystallization.

(b)(i) List two normal salts which when dissolved in pure water are acidic to litmus

(ii) Mention the phenomenon that accounts for the behaviour of the salts in (b)(i) above.

(c)(i) Outline a suitable laboratory method for separating a mixture of glucose and starch.

(i) Give two chemical tests that would enable you to identify three solids suspected to be glucose, sucrose and starch.

You are provided with two aqueous solutions labelled C and D. Carry out the following exercises on them. Record your observations and identify any gases evolved. State the condition you draw from the result of each test.

(a)(i) Mix C and D in a beaker thoroughly.

(ii) Filter the mixture. Keep both the residue and the filtrate.

(b)(i) To about 5cm\(^3\) of the filtrate, add barium chloride solution, followed by excess dilute hydrochloric acid in a boiling tube. Divide the resulting solution into two portions.

(c)(i) To the first portion of the solution from (b)(ii) above, add sodium hydroxide solution in excess.

(ii) To the second portion of the solution from (b)(ii) above, add aqueous ammonia in drops until it is in excess.

A solution containing 0.095 mol. dm\(^{-3}\) of trioxonitrate (V) acid. Solution B contains 13.50g of X\(_2\)CO\(_3\).10H\(_2\)O per dm\(^3\)

(a) Put A in the burette and titrate with 20cm\(^3\) or 25cm\(^3\) portions of B using methyl orange as an 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) molar mass of X\(_2\)CO\(_3\).10H\(_2\)O

(iii) percentage by mass of X in X\(_2\)CO\(_3\).10H\(_3\)O. The equation for the reaction is X\(_2\)CO\(_3\) + 2HNO\(_3{(aq)}\) \(\to\) 2XNO\(_{3(aq)}\) + CO\(_{2(g)}\) + 11H\(_2\)O\(_{(l)}\) [H = 1, C = 12, O = 16]

(c) Give the reason for the following:
(i) using just a small quantity of the indicator during acid-base titrations.

(ii) obtaining at least two sets of readings for titration experiment.

(a)(i) Define a standard solution

(ii) Give the reason why a standard solution of sodium hydroxide cannot be made by weighing out accurately a given mass of the solid and making it up to the required volume of solution

(b) Give two ways by which a solid solute can be made to dissolve more quickly in a liquid Solvent

(i) Draw a labelled diagram of the apparatus used for drying solids in the laboratory

(c) State what would be observed if a fresh precipitate of silver chloride was;

(i) Exposed to light.

(ii) Shaken will excess aqueous ammonia