9647 CHALLENGING QUESTIONS (NO ANSWER) .

1. A student tried to synthesize 1-amino-4-methyl-benzene from phenylamine, CH3Cl, and AlCl3. He also tried to synthesize

butylbenzene from benzene, 1-bromobutane, and FeBr3. By drawing reaction mechanisms, explain why both experiments

failed.

2. 50cm3 of aqueous sulfuric(VI) acid of unknown molarity was mixed with 75cm3 of 0.45mol/dm3 of aqueous potassium

hydroxide. 55cm3 of the resulting alkaline solution A was mixed with 80cm3 of 0.35mol/dm3 of phosphoric(V) acid. 90cm3

of the new resulting acidic solution B required 39.97cm3 of aqueous sodium carbonate of unknown molarity, for complete

neutralization. In a separate experiment, 625cm3 of the same aqueous sulfuric(VI) acid solution required 192.3cm3 of the

same aqueous sodium carbonate solution for complete neutralization.

a) Calculate the molarities of the sulfuric(VI) acid solution and the sodium carbonate solution.

b) Draw the full displayed structural formulae of sulfuric(VI) acid, potassium hydroxide,

phosphoric(V) acid, sodium carbonate, and the salts in solution A and solution B.

3. For gases, there exists a formula that describes the relationship of the variables of Pressure, Volume, no. of moles,

Temperature :

PV = nRT (where R is a constant mathematical value).

If these units (pressure in Pa; volume in m3) are used, the value of the gas constant R is 8.314. If these units (pressure in

atm; volume in dm3)

are used, the value of the gas constant R is 0.08206. Temperature is always measured in Kelvins (where 298K = 25C;

273K = 0C).

A bubble of gas (initial diameter 1.585 cm; mass 2.0973 x 10-2 g) that contains twice as much oxygen as it does carbon

dioxide, emerges from a photosynthesizing aquatic plant (theres a plesiosaur reptile aka Loch Ness monster right next

to the plant, btw) at the bottom of a lake, where the temperature is really cold and the pressure is 6.4 times greater than at

the lakes surface; and the bubble rises until it reaches the surface of the lake (which happens to be at sea level, and at

that moment is equivalent to room temperature), and bursts pop!.

(i) Calculate the diameter (in cm) of the bubble just before it bursts.

(ii) Calculate the body temperature (in C) of the plesiosaur at the time the bubble emerges.

4. a) When O, C4H6O6, is heated with concentrated sulfuric(VI) acid, two possible products M and G with molecular

formulae C4H2O4 and C8H8O10 are formed as a result of intramolecular and intermolecular esterifications, respectively.

Elucidate O, M, G.

b) A compound Y has molecular formula C6H10. 1 mol of Y reacts with 2 mol of aqueous bromine. On reaction with hot,

concentrated, acidified KMnO4(aq), compound Y yields only an acidic gas and a compound X, which when reacted with

LiAlH4 (in dry ether) followed by protonation, yields a primary alcohol that gives a yellow precipitate with alkaline aqueous

iodine. Elucidate X and Y.

c) Compound A C13H15O3Cl decolourises hot acidified KMnO4 forming B, C, and D with formulae C4H8O3, C3H4O3,

C6H5OCl respectively. 1 mol of B reacts with 0.5 mol of Na2CO3 and reacts with concentrated H2SO4 to give sweet

smelling E C8H12O4. C gives a positive idoform test and reacts with SOCl2. D reacts with aqueous Br2 to form a white

precipitate. Elucidate A to E.

d) Draw an optically active molecule consisting of 12-C, 1-H and 79.9-Br, with a relative molecular mass of 278.7 (indicate

chiral C with *).

5. In an episode of "The Simpsons", Bart mixes nitric(V) acid with ethanol, with the result of a gas being produced. Indeed,

this would occur; a total of 5 different possible products, involving 2 separate reaction pathways, may be obtained. Write

equations for these 2 reaction pathways; identify and draw the structures of the 5 products; draw the mechanism for one

of these two pathways.