Sch2106:Physical Chemistry Question Paper
Sch2106:Physical Chemistry
Course:Bachelor Of Horticulture
Institution: Meru University Of Science And Technology question papers
Exam Year:2014
QUESTION ONE – (30 MARKS)
(a) (i) Define the term solubility product of a binary electrolyte. (1 Mark) (ii) Calculate the solubility product of lead chloride at 25°?? given that its solubility at this temperature is 4.75??????-3 ???? = 207,???? = 35.5 (3 Marks)
(b) What is the oxidation number of chlorine in each of the following? (i) ????????2 (ii) ????2??3 (iii) ????????4 (3 Marks)
(c) Calculate the volume in mls of a 2.84?? ???????? solution required to titrate 25mls of 2.25M ??2????4. (3 Marks)
(d) The Van der Waals equation for one mole of gas is often used to describe the behavior of real gases. ? ?? ? RT bv v p ? ??? 2 where ??and b are constants. Suggest reasons for the
2v ? and b in this equation. (2 Marks)
(e) Write the expression for the sp K of the following
2
(i) ????????4
(ii) ????2????3
(iii)??????????3 (3 Marks)
(f) (i) Distinguish between electrolytic and electrochemical cell. (2 Marks) (ii) Given the standard reduction potential below. ????2+ + 2?? ? ???? + 0.34?? ????2+ + 2?? ? ???? - 0.76?? ????3+ + ?? ? ????2+ - 0.44?? ????4+ + ?? ? ????3+ + 1.76??
i. Identify the strongest oxidising agent (1 Mark) ii. State the two uses of electrode potentials. (2 Marks) iii. Predict the cell reaction that gives the highest e.m.f. (2 Marks)
(iii) State the functions of a salt bridge in an electrochemical cell. (2 Marks) (g) (i) Define the term ???? (1 Mark) (ii) What is the pH of 0.011M solution of ???? ???? 2? (3 Marks)
(h) Explain the term common effect. (2 Marks)
QUESTION TWO – (20 MARKS)
(a) (i) Define the term buffer solution. (1 Mark) (ii) Calculate the pH of 0.1?? ????4????, ???? = 1.8 × 10-5 (3 Marks)
(b) Briefly, discuss the ionization of water. (3 Marks) (c) Classify the following into Lewis acids and bases ??2-,????+,????3,??2??5???? (2 Marks) (d) A sample of fertilizer has a pH of 8.54. Calculate the hydrogen ion concentration of this fertilizer. (2 Marks) (e) Water gas reaction is represented by the equation. ??(??) + ??2??(??) ? ????2 (??) + ??2 ?? ??? = +131.4???? ??????-1
Answer the following questions in respect of it. (i) What is the equilibrium law expression for it? (2 Marks) (ii) State, giving reasons how this equilibrium will shift if i. All pressures are doubled (2 Marks) ii. The temperature is increased (2 Marks) iii. Anhydrous CaCl2 is added iv. A leaking vessel is used maintaining supply of steam constant. (1 Mark)
3
QUESTION THREE – (20 MARKS)
(a) Distinguish between electrolyte and conductors. (2 Marks) (b) State two causes of deviations of real gas from ideal gas behavior. (2 Marks) (c) The solubility product of ???????? is 1.5 × 10-10. What weight of ???????? will be dissolved in 100mls of (i) Water (2 Marks) (ii) A solution containing 0.234?? of ???????? (3 Marks) (iii)A solution containing 0.17?? of ????????3 (3 Marks)
(d) What are the conjugate bases of ; (i) ????-
(ii) ??3??+
(iii) ???? ??2?? 6 3+ (3 Marks)
(e) The reaction between Sodium Sulphite and Potassium permanganate in acidic medium is represented is represented as ????2????3 + ??+ + ????????4 ? ????2????4 + ??2?? + ????2+. Write a balanced ionic chemical equation. (5 Marks)
QUESTION FOUR – (20 MARKS)
(a) Define the following terms (i) Ideal gas (1 Mark) (ii) Acid-base indicator (2 Marks)
(b) (i) What is meant by the term dynamic equilibrium? (1 Mark) (ii) State two criterion for an chemical equilibrium. (2 Marks)
(c) Use the data below to calculate the enthalpy of formation of propane. ? ? ?
????
???
???
KJmolOHCOOHC
KJmolOHOH
KJmolCOOC
lggg
lgg
Gs
0.2220435
9.285
2 1
5.393
)(2)(2)(2)(83
)(2)(2)(2
)(22)(
(d) Explain the following observation (i) ????2????3 in water is basic (2 Marks)
(ii) ????2????4 in water is acidic (2 Marks)
(e) pK value of acetic acid is 4.76 at room temperature. How will you obtain buffer of 4.40 values from acetic acid and sodium acetate. (4 Marks) (f) State two colligative properties of solution of non-volatile solutes. (2 Marks)
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