THE UNITED REPUBLIC OF TANZANIA NATIONAL EXAMINATIONS COUNCIL OF TANZANIA ADVANCED CERTIFICATE OF SECONDARY EDUCATION EXAMINATION
132/1 CHEMISTRY 1
(For Both School and Private Candidates)
Time: 3 Hours Year: 2014
1. This paper consists of sections A and B with a total of ten (10) questions.
2. Answer all questions in section A and two (2) questions from section B.
3. Each question carries ten (10) marks in section A and fifteen (15) marks in section B.
4. Mathematical tables and non-programmable calculators may be used.
5. Cellular phones and any unauthorised materials are not allowed in the examination room.
6. Write your Examination Number on every page of your answer booklet(s).
7.For calculations, you may use the following
Rydberg constant, RH =1.09678x 107m-1
Gas constant, R = 8.31JmoI-1K-Ior 0.0082 atm mol-1 K-Idm3
GMVat s.t.p. 22.4dm3
1 litre = 1 dm3=1000cm3
At STP: Temperature = 273K, Pressure = 760mmHg
Planck constant, h=6.63x 10-34Js
Velocity of light, C = 3.0 x 108m/s
Atomic masses H = 1, C = 12, N = 14, O-16, Na-23
1. Nitrogen and oxygen combine endothermic ally at elevated temperature according to the equation 2N 2(g) +O2(g) 2NO2(g)• If the equilibrium constant for the reaction is4.3x10-3 at 30000C and I atm, calculate the composition of each in the equilibrium if 2 moles of each nitrogen and oxygen were heated.
(b) When 20.85g of PC15 was heated in a sealed tube of 4 dm3volume, the pressure in the vessel was found to be 1.5 atm. At this pressure it was found that PCI5 dissociated to 80%. Calculate the partial pressure of each gas.
6. (a) A solution is prepared from 90g of water and 10.6g of a non- volatile, non-dissociating solute. The vapour pressure of the solution at 600C is found to be 18.91x103Nm-2, Calculate the approximate molecular mass of the solute given that, the vapour pressure of water at 600C is 19.92Nm-2
(c) Two isomeric hydrocarbons P and Q have molecular formula C9H12. On oxidation, P gives monocarboxylic acid, when treated with soda lime yields benzene. Q is oxidized to give tricarboxylic acid and can undergo nitration reaction to give two mono-nitro derivatives.
(i) Write down the structural formula of P and Q
(ii) Write an equation to show how Q is oxidized to give tricarboxylic acid.
(iii) Name the compound which is formed when P undergoes oxidation.
(c) The displacement of a particle from the equilibrium position moving with simple harmonic motion is given by x = 0.05 sin6t where t is time in seconds measured from an instant when x = 0. Calculate the:
(ii) A disc of moment of inertia2.5 x 10-4 kgm2 is rotating freely about an axis through its centre at 20rev/min. If some wax of mass 0.04kg is dropped gently onto the disc 0.05m from its axis, what will be the new revolution per minute of the disc?