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Fst 2109- Introduction To Physical Chemistry Question Paper

Fst 2109- Introduction To Physical Chemistry

Course:Bachelor Of Food Science

Institution: Dedan Kimathi University Of Technology question papers

Exam Year:2012

FST 2109- Introduction to Physical chemistry, Semester- 2 2011/2012 Page 1 of 3
KIMATHI UNIVERSITY COLLEGE OF TECHNOLOGY
UNIVERSITY EXAMINATIONS 2011/2012
YEAR ONE SEMESTER I EXAMINATION FOR DEGREE OF
BACHELOR OF SCIENCE – FOOD SCIENCE
DATE: DECEMBER 2011 TIME: 2 Hours
INSTRUCTIONS: Answer Question ONE and any other TWO questions
QUESTION ONE (30 MARKS)
a) Define the term “azeotropic” mixture (2 marks)
b) Distinguish the following between
i. Electrolytes and conductors (2 marks)
ii. Charles’ law and Boyle’s law (2 marks)
c) State four important colligative properties exhibited by dilute solutions containing
non-volatile solutes (4 marks)
d) State two causes of deviations of real gases from ideal behaviour (2 marks)
e) State Le chaterier’s principle (1 marks)
In the reaction N2 + 3H2 ?2NH3 ?H=92kJmol-1 (3 marks)
(i) State how an increase in temperature will affect the yield of ammonia
(ii) State the other two optimum conditions, for the manufacture of ammonia,
apart from the temperature
f) State three main postulates of kinetic theory of gases (3 marks)
g) (i) Define the term solubility product of a binary electrolyte (1 mark)
(ii)Calculate the solubility product of lead chloride at 25oC given that its solubility at
this temperature is 4.75 g litre-1 (Pb=207, Cl=35.5) (4 marks)
h) The Van der Waals constant for methane (CH4) are a=2.25 atm l2 mol-2 and b= 0.043l
mol-1. Calculate its critical constants (3 marks)
i) State three characteristics of a chemical equilibrium (3 marks)
QUESTION TWO (20 marks)
a) Write the expression for the Ks.p of the following (2 marks)
(i) Ag2CO3 (ii) AgBrO3
b) 100 cm3 of HCl were found to diffuse through a porous plug in 42.5s, while the
same volume of nitrogen compound diffused in 29.3s under the same conditions.
Calculate the relative molecular of nitrogen compound (H=1, N=14, Cl=35.5)
(3
marks)
c) Two moles of ammonia are confined to a 5-litre flask at 27OC. Calculate its
pressure using
(i) The gas equation (2 marks)
(ii) The Van der Waals’ (3 marks)
(a = 4.17 atm l2 mol-2, b = 0.0371 lmol-1)
d) Classify the following into Lewis acids and bases: S2-, BF3, Cl-, C2H5OH, (CH3)3N,
Ag+ (2mark)
e) Calculate the volume in ml of a 2.84 M NaOH solution required to titrate 25 mls of
2.25 M H2SO4 (3 marks)
f) i) State Dalton’s law of partial pressure (2 marks)
ii) An enclosed vessel contains 2.8g of nitrogen and 14.2 g of chlorine at 101.3 kpa
and 0 oC. What will be the partial pressure of nitrogen if the temperature is raised to
180 oC. (3 marks)
QUESTION THREE (20 marks)
a) Distinguish between homogeneous and heterogeneous equilibrium (2 marks)
b) Explain the following observation sodium acetate solution turns litmus blue
(2 marks)
c) In a titration, 23.8 cm3 of a solution of ethanoic acid (CH3COOH) were
neutralized by 25.0cm3 of 0.1059 M sodium hydroxide solution while, in a
separate experiment, the acid solution was found to have a pH of 2.86. Calculate
the Ka for ethanoic acid (5 marks)
d) The solubility product of BaSO4 in H2O is 1.6 x 10-9 mol2 dm-6. Calculate the
solubility in mol dm-3 in pure water (2marks)
e) Using suitable examples, give three common forms of colloidal solution (3marks)
f) At 267 OC, 10.425 g of PCl5 are heated in a 4 l flask. The equilibrium mixture had
a pressure of 1 atm. Calculate Kp, Kc and ?G0 for the reaction at 267 OC. (P = 31,
Cl = 35.5) (4 marks)
g) Calculate the mass of nitrogen gas which exerts a pressure of 2.5x 105 pa in a
300cm3 vessel at 20oC (N=14, R=8.31 Jmol-1K-1) (2 marks)
QUESTION FOUR (20 marks)
a) Define the following terms (2 marks)
i. Critical temperature
ii. Critical pressure
b) State Raoult’s law of partial pressure (2 marks)
c) Distinguish between electrolytic cell and electrochemical cell (2 marks)
d) 10g of an impure iron (ii) salt were dissolved in water and made up to 200cm3 of
solution. 20cm3 of this solution, acidified with dilute H2SO4, required 25cm3 of
0.04 mol dm-3 KMnO4 solution before a faint colour appeared.
i. Write a balanced ionic equation for the reaction of acidified manganate (vii)/
permanganate ions with iron (ii) ions (4 marks)
ii. How many moles of iron (ii) ions react with one mole of MnO4
- ions? (1 mark)
iii. How many grams of Fe2+ are there in the 200cm3 of the original solution (Fe = 56)
(2 marks)
iv. Calculate the percentage by mass of iron in the impure iron (ii)salt (2 mark)
e) NH4Cl aqueous solution turns litmus red. Explain this observation (2 marks)
f) State two limitations of solubility products (3 marks)
QUESTION FIVE (20 marks)
a) State Avogadro’s law (1 mark)
b) Predict whether there will be any precipitation on mixing 50 ml of 0.001M NaCl
solution with 50 ml of 0.01 M AgNO3 solution. Ksp (AgCl) = 1.5 x 10-10 (4 marks)
c) The solubility product of AgCl is 1.5 x 10-10. What weight of AgCl will be
dissolved
i. In 100 ml of water (3 marks)
ii. In a solution containing 0.234g of NaCl in 100 ml (3 marks)
iii. In a solution containing 0.0.17 g of AgNO3 in 100 ml (3 marks)
d) What will be the equilibrium concentration of H2, I2 and HI if, initially, 5
millimoles of H2 and 2 millimoles of I2 are introduced in a one-litre flask
thermostated at 27 oC? (Kc for the reaction is 16.34 at 27 oC) (5 marks)

Fst 2109- Introduction To Physical Chemistry Question Paper

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