Sch2106:Physical Chemistry Question Paper
Sch2106:Physical Chemistry
Course:Bachelor Of Horticulture
Institution: Meru University Of Science And Technology question papers
Exam Year:2013
QUESTION ONE (30 MARKS)
a) Using graphs and examples of reaction to explain the meaning of the following reactions i. Endothermic reactions. (4 Marks) ii. Exothermic reactions. (4 Marks) b) Given the reactions;
H3C C
CH3
CH3
Br CH3 C+
CH3
CH3
+ :Br-
CH3 C+
CH3
CH3
:OH- CH3 C
CH3
CH3
OH
CH3CH2Br + OH- CH3CH2OH + Br-
I
II.
2
i. Write an expression for rate law in the two reactions. (2 Marks) ii. State the order of reaction in each case. (2 Marks) iii. In reaction one, state the rate determining step. Explain (2 Marks) iv. Explain the reasons for the differences in question b(ii). (4 Marks) c) i) Write the expression for Arrhenius equation. (2 Marks) ii) State the meaning of term involved. (4 Marks) d) i) Given that 0.447g of a common chloroflorocarbon in a 100ml flock exerts a pressure of 758mmHg at 100°??. What is its molar mass? (2 Marks) ii) 12.0L of an ideal gas at 600°?? and 2.25atm are expended to 16.02 and increased in temperature to 120°??. What is the new pressure of the gas? (2 Marks) iii) What factors cause a real gas to net to obey the ideal gas equation? (2 Marks)
QUESTION TWO (20 MARKS)
a) Using a graph describe the effect on the distributions of molecules of gas at the following temperatures. i. 100k ii. 300k iii. 1000k (8 Marks) b) Explain the appearance in the stated shape in 2(a) above. (3 Marks) c) 250cm3 of a gas is collected over acetone at -10oC and 85cm. If the gas weighs 1.34g and the vapor pressure of acetone at 10° ??, is 39mm. What is the molecular mass of the gas? (9 Marks)
QUESTION THREE (20 MARKS)
a) Given the dissociation constant (Ka) for acetic acid is1.8 × 10-5. Calculate the degree of ionization of 0.4 as acetic acid solution in water. (6 Marks) b) State the physical meaning of the following terms; i. Solubility product ii. Dissociation constant iii. pH iv. pKb (4 Marks) c) Sketch the titration curves for the following reactions i. Dilute HCl and dilute NaOH. (2 Marks) ii. Dilute CH3COOH and dilute NaOH. (2 Marks) iii. Dilute CH3COOH and NH4OH. (2 Marks) d) Using above 7, below 7 and at 7, state the equivalent point for reaction (i) and (iii). (2 Marks)
QUESTION FOUR (20 MARKS)
a) In a cell one electrode is made of silver metal immersed in 0.01 mol solution of silver nitrate. The second electrode is made of platinum over which hydrogen gas at 1
3
atmospheric pressure is bubbled and is dipped in a solution of unknown pH. What is the pH of solution if the cell potential is 1.04V? (12 Marks) b) The equivalent conductance at 25°?? of a 0.05m solution of acetic acids is 7.36. What is constant of the acid? (4 Marks) c) The specific conductance at 25°?? of a suspension silver chloride in water was determined to be 1.826 × 10-6?-1. The infinite dilution ionic conductance of Ag+ and Cl- are 61.92 and 76.34 respectively. Calculate the solubility products of AgCl. (4 Marks)
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