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Fst 2109- Physical Chemistry Question Paper
Fst 2109- Physical Chemistry
Course:Bachelor Of Food Science
Institution: Dedan Kimathi University Of Technology question papers
Exam Year:2012
FST 2109- 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
Special/ supplementary examination
DATE: DECEMBER 2011 TIME: 2 Hours
INSTRUCTIONS: Answer Question ONE and any other TWO questions
QUESTION ONE (30 MARKS)
QUESTION 1
a) Distinguish the following between
i. Electrolytes and conductors (2 marks)
ii. Molarity and normality (2 marks)
b) Define the colligative properties of dilute solutions (1 mark)
c) State Charles’ law. Explain Charles’ law using kinetic theory of gases (3 marks)
d) State two causes of deviations of real gases from ideal behaviour (2 marks)
e) 100 cm3 of HCl were found to diffuse through a porous plug in 43s, 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)
f) State three main postulates of kinetic theory of gases (3 marks)
g) Explain the following observation. Acidity increases in the order;
HClO < HClO2 < HClO3 < HClO4 (2 marks)
h) (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) (3 marks)
i) Explain the following observations
i. Sodium acetate solution turns litmus blue (2 marks)
ii. Ammonium chloride solution turns litmus red (2 marks)
j) What is the oxidation number of chlorine in each of the following?
(i) HClO2 (ii) Cl2O3 (2 marks)
k) Calculate the volume in ml of a 2.84 M NaOH solution required to titrate 25 mls of 2.25 M H2SO4 (3 marks)
l) Calculate the mass of oxygen which exerts a pressure of 1.01x105 pa in a 300cm3 vessel at 27oC (O=16, R=8.31 Jmol-1K-1) (3 marks)
m) State the functions of a salt bridge in an electrochemical cell (2 marks)
n) Discuss two factors that affects viscosity of a liquid (2marks)
QUESTION 2
a) State two uses of solubility product concept (2 marks)
b) 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)
c) i)Explain the term oxidation number (1marks)
ii) Given the standard reduction potentials below
Sn+4 +2e? Sn+2, E? =0.15V
Fe+3 +e ? Fe+ 2, E? =0.77V
Predict the cell reaction and calculate E? cell given that (3 marks)
d) AAt 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)
e) Explain how the following factors affect the equilibrium H2 + I2 ?2HI (2 marks)
i) Catalyst
ii) Addition of inert gas
f) A sample of freshly prepared juice has a pH of 8.54. Calculate the hydrogen ion concentration of this juice (3 marks)
QUESTION 3
a) Define the term pH (1 mark)
b) Describe two intermolecular attractions (4 marks)
c) State Hess’s law (1 marks)
d) Identify the Bronsted acid and its conjugate base (2 marks)
HF+ NH3 ? NH4+ + F-
e) The reaction between sodium sulphite and potassium permanganate in acidic solution is represented as
Na2SO3 + H+ +KMnO4 ? Na2SO4 + H2O +Mn 2+
a. Why is it not advisable to acidify using HCl or HNO3 (2 marks)
b. Write a well balanced ionic chemical equation (6 marks)
f) The solubility product of BaSO4 in H2O is 1.6 x 10-9 mol2 dm-6. Calculate the solubility in mol dm-3 in:
i. Pure water (2marks)
ii. 0.1 M Na2SO4 (2 marks)
QUESTION 4
a) Distinguish between electrolytic cell and electrochemical cell (2 marks)
b) Define the following terms (4 marks)
i. Enthalpy of formation
ii. Enthalpy of combustion
c) Use the data below to calculate the enthalpy of formation of propane (3 marks)
C (graphite) + O2? CO2 (g) + 393.5 kJmol-1
H2 (g) + ½ O2 (g) ? H2O (l) + 285.9 kJmol-1
C3H8 (g) + 5O2 (g)? 3CO2+ 4H2O + 2220.0 kJmol-1
d) The Van der waals equation for one mole of a gas is often used to describe the behaviour of real gases.
(P + a/V2) (V-b) = RT, where a and b are constants.
Suggest reasons for the a/V2 and b in this equation. (2 marks)
e) Using Lewis concept, define an acid (1 marks)
f) State Dalton’s law of partial pressure (2 marks)
g) Name two electrodes that can be used during electrolysis (2 marks)
h) 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. (4 marks)
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