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Sch2102:Atomic Structure Question Paper
Sch2102:Atomic Structure
Course:Bachelor Of Science
Institution: Meru University Of Science And Technology question papers
Exam Year:2014
QUESTION ONE (30 MARKS)
a) Define the following terms i. Buffer solution (1 Mark) ii. Azeotropic mixture (1 Mark) iii. Critical temperature (1 Mark) b) State three colligative properctal exhibited by dilute solution containing non – volatile solutes. (3 Marks) c) State Le-Chateliers principle. (1 Mark) d) Using Van der Waal’s equation, calculate the pressure of ethanol vapour at 82°??. If one mole of ethanol occupies 35dm3, for ethanol gas [a=12.02 L2atm mol2-, b=0.8407l mol-1 and R=0.082atm mol-]. (4 Marks) e) State two limitations of solubility product concept. (2 Marks) f) State three main postulates of Kinetic Theory of gases. (3 Marks) g) A sample of freshly prepared juice has a pH of 7.4. Calculate the hydrogen ion concentration. (2 Marks) h) State two causes of deviations of real gases from ideal behaviour. (2 Marks) i) Given the standard reduction potentials below ????2+ + 2?? ? ???? + 0.34?? ????2+ + 2?? ? ???? - 0.76?? ????2+ + ?? ? ????2+ - 0.44?? ????4+ + ?? ? ????3+ + 0.76?? i. Identify the strongest oxidizing agent. (1 Mark) ii. State two uses of electrode potentials. (2 Marks) iii. Predict the cell reaction that gives the highest emf. (1 Mark)
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j) In a titration 23.8cm3 of a solution of ethanoic acid (CH3COOH) were neutralized by 25.0cm3 of 0.1059M sodium hydroxide (NaOH) solution while in a separate experiment, the acid was found to have a pH of 2.86. Calculate the Ka value for ethanoic acid. (6 Marks)
QUESTION TWO (20 MARKS)
a) Define the term acid-base indicator. (1 Mark) b) The solubility product of AgCl is 1.5 × 10-10??????2????-6. What weight of AgCl will be dissolved in i. 100 ml of water. (2 Marks) ii. A solution containing 0.23g of NaCl in 100ml. (3 Marks)
???? = 108,???? = 35.5,???? = 23,?? = 1,?? = 16
c) The reaction between sodium sulphite and potassium permanganate in acidic medium is represented as ????2????3 + ??+ + ????????4 ? ????2????4 + ??2?? + ????2+ i. Why is it not advisable to acidity using HCl? (1 Mark) ii. Write a well balanced ionic equation. (6 Marks) d) State Raoult’s law of partial pressure. (1 Mark) e) The dissociation constant of a base at 25°?? is 1.5 × 10-10. What is; i. The concentration of hydroxyl ions in 0.015 molar solution? (2 Marks) ii. Its degree of dissociation? (2 Marks) f) State the functions of a salt bridge in an electrochemical cell. (2 Marks)
QUESTION THREE (20 MARKS)
a) i) Define the term solubility product. (1 Mark) ii) Calculate the solubility product of lead chloride at 25°??. Given that its solubility at this temperature is 4.75gl-1. [Pb=207, Cl=35.5]. (3 Marks) b) A sample contains 0.1M of each CH3COOH and CH3COONa. What will be the change in pH on adding i. 0.01M HCl to 1 litre solution. (3 Marks) ii. 0.01M NaOH to 1 litre solution ???? = 1.8 × 105 . (4 Marks)
(Assume no charge in volume occurs on additions of HCl or NaOH)
c) Identify the Bronsted acid and its conjugate base i. ??2????(????)4 + ????3???? ? ??????(????)4 - + ????3????2 + . (1 Mark) ii. ???? + ????3 ? ????4 + + ??-. (1 Mark) d) Determine the oxidation number of element in the brackets in the following compounds: i. ???? ???? ??2????2??7. (2 Marks) ii. ???? ???? ????????4. (2 Marks)
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e) Calculate the mass of nitrogen gas which exerts a pressure of 2.5 × 105???? in a 300cm3 at 20°??. (N=14, R=8.314Jmol-1K-1). (3 Marks)
QUESTION FOUR (20 MARKS)
a) Distinguish between electrolytic and electrochemical cell. (2 Marks) b) An enclosed vessel contains 2.8g of nitrogen and 14.2g of chlorine at 101.3kPa and 0°??. What will be the partial pressure of nitrogen if the temperature is raised to 180°??. (4 Marks) c) State three characteristics of a chemical equilibrium. (3 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, requires 25cm3 of 0.04M KMnO4 solution before a faint colour appeared. i. Write a balanced ionic equation for the reaction of acidified manganate (VII) ions with iron (ii) ions. (3 Marks) ii. How many moles of iron (ii) ions react with one mole of ??????4 - ions? (2 Marks) iii. How many grams of ????2+ 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 salt. (1 Mark) e) Explain the following observations i. ????4???? aqueous solution turns litmus red. (2 Marks) ii. State two factors that affects viscosity of a liquid. (1 Mark)
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