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Sch 203: Thermodynamics 1 And Thermochemistry Question Paper

Sch 203: Thermodynamics 1 And Thermochemistry

Course:Thermodynamics And Thermochemistry

Institution: University Of Nairobi question papers

Exam Year:2014

UNIVERSITY OF NAIROBI
SECOND SEMESTER EXAMINATION FOR THE DEGREE OF BACHELOR OF PHARMACY LEVEL I
SCH 203:THERMODYNAMICS 1 AND THERMOCHEMISTRY I
DATE: 2/7/2014 TIME:9.00 A.M -11.00 A.M

INSTRUCTIONS
Answer all questions

1. a) Give the meaning of the following thermodynamic concepts. (6 marks)
i) System
ii)Surrounding
iii) Extensive property
iv)Intensive property
v) State function
vi) Thermal equilibrium

b) i) Define the first law of thermodynamics (1 mark)
ii) Give the mathematical expression of the first law of thermodynamics (1 mark)
iii) Write the differential form of the law (1 mark)
iv) Give the meaning of internal energy (1 mark)

c) i) A piston in a cylinder containing hydrogen and oxygen gases. As the reaction occurs the system
loses 550J of heat to the surroundings.The expanding gas does 240J of work on the surrounding.
Calculate the change in internal energy of the system. (2 marks)
ii) A gas is placed in a cylinder and allowed to expand. Show that the magnitude of the work(W)done
by expanding the gas can be represented by the following expression
W=PdV Where P-Pressure of the gas and dV- change in volume of the gas (3 marks)
iii) A solution containing silver ions (Ag^+) is mixed with a solution containing chloride ions (Cl^-)
Calculate the change in enthalpy (dH) in the reaction given that: (3 marks)
Enthalpy of formation under standard condition
AG^+(aq) +105.9 kJ/mol
Cl^-(aq) -167.2 kJ/mol
AgCl(s) -127.0 kJ/MOL

2. a) i) Outline with the help of a diagram the compression of a gas and prove the the work done by compression
is positive. (6 marks)
ii) Name any FOUR conditions required for compression of a gas in a cylinder. (4 marks)
b) i) Evaporation of water and condensation of water are represented in the following equation
H2O(l) -------->H20(g) - Evaporation
H2O(g) -------->H20(l) - Condensation
Give the data below
Enthalpy of formation under standard condition
H2O(l) -285.83 kJ/mol
H20(g) -241.82 kJ/mol
Calculate the standard change in enthalpy for each reaction above and state which reaction is
endothermic or exothermic. (3 marks)
ii)A certain gas expands from 4.0L to 8.0L at constant temperature. Calculate the work done by the gas if
it expands against:
a) Vacuum
b) A constant pressure of 2.4 atm
Convert the work done to Joules. (1L-atm = 101.3J) (4 marks)

Sch 203: Thermodynamics 1 And Thermochemistry Question Paper

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