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SBPH 2203
THERMODYNAMICS
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ASSIGN MENT QUESTION

QUESTION/SOALAN 1

a) Calculate the amount of energy (in joules) that must be removed from 200 g of water initially at 95ºC in order to completely freeze it to ice at -5 ºC.

Use the following data:
Specific heat capacity of water = 4190,
Specific heat capacity of ice = 2220,
Heat of fusion of water = 333

b) A block of metal has dimensions 10 cm × 10 cm × 10 cm at 27ºC. Calculate
i) the change in the volume
ii) the new volume of the block if its temperature increases to 127ºC.
(The coefficient of volume expansion of the block is)

[10 marks/markah]

QUESTION/SOALAN 2

a) The tungsten filament of an electric lamp has a length of 0.50 m and a radius of . The power rating of the lamp is 50 W. Estimate the temperature of the lamp if its emissivity is 40 % that of a black-body.

b) An ideal gas of molar mass 30 g/mol is contained in a cylinder of volume 1× The temperature of the gas is 37ºC and its pressure is 2 atm.
i. Calculate the number of molecules of gas present in the cylinder.
ii. Calculate the new pressure of the gas if the volume of the cylinder is halved but the temperature is tripled.

[10 marks/markah]

QUESTION/SOALAN 3

a) 0.01 kg of oxygen gas is enclosed in a container at a temperature of 20ºC. Calculate the amount of heat that has to be transferred to the gas to double its r.m.s speed.

b) i. Obtain the r.m.s speed of helium atoms at 900 K.
ii 1 mole of this gas is now confined to a cube of side 10 cm. Calculate the
pressure developed in the cube.
(Molar mass of Helium = 4 g/mole, R = 8.31 J/mole.K)

[10 marks/markah]

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