Molecular Physics | Thermodynamics Answers

show that entropy increase when two gases mix.

Show that entropy S and thermodynamic
probability W for a completely ordered
system is S = k in W.

Show that entropy S and thermodynamic
probability W for a completely ordered
system is S = k in W.
Define entropy. Calculate the change in entropy
when two gases kept in separate containers are
allowed to mix.

Water at a temperature of 15°C produces ice cubes at a temperature of −5°C. Water is taken in at the
rate of 1 kg every 7 minutes and the input power to the machine is 300 W. The specific heat capacity of
water is 4187 Jkg−1K

−1, the specific heat capacity of ice is 2100 Jkg−1K

−1 and the specific latent heat of

fusion is 335 Jkg−1
i) Calculate the heat energy extracted per kg of ice produced
ii) Calculate the thermal efficiency of the ice making machine.

The length of Lead piping in the plant is 50 m long at a temperature of 160C. When hot water flows
through it the temperature of the pipe rises to 800C. The coefficient of linear expansion of lead is
29 10-6 0 K-1
i) Determine the change in length of the hot pipe.
ii) Determine the compressive force induced in the pipe if it is rigidly held and expansion is
prevented.

The wall of a house consists of two 125 mm thick brick walls with an inner cavity. The inside wall has a 10 mm coating of plaster, and there is a cement rendering of 5 mm on the outside wall. In one room of the house the external wall is 4 m by 2.5 m, and contains a window of 1.8 m by 1.2 m of 1.5 mm thick glass. The heat transfer coefficients for the inside and outside surfaces of the wall and window are 8.5 and 31 W/m2K respectively. The thermal conductivities of brick, plaster, cement, and glass are 0.43, 0.14, 0.86, and 0.76 W/mK respectively. Assuming that the resistance of the air cavity is 0.16 m2K/W, neglectign all end effects, and neglecting radiation, calculate the proportion of the total heat transfer which is due to the heat loss through the window.

An electric hot-plate is maintained at a temperature of 350C and is used to keep a solution just boiling at 95 C. The solution is contained in an enamelled cast-iron vessel of wall thickness 25 mm and enamel thickness 0.8 mm. the heat transfer coefficient for the boiling solution is 5.5 k W/ m2 K, and the thermal conductivities of cast iron and enamel are 50 and 1.05 W/m K respectively . Calculate the resistance to the heat transfer for unit area, and the rate of heat transfer per unit area, then recalculate the rate of heat transfer per unit area if the base of the cast-iron vessel is not perfectly flat,and the resistance of the resultant air film is 35 m2 K/ kW.

A furnace wall consists of 250 mm firebrick, 125 mm insulating brick,
and 250 mm building brick. At the inner wall, the temperature is
measured to be 600° C and the atmospheric temperature is 20'C. The
heat transfer coefficient for the outside surface is 10 W/m2
.K, and
the thermal conductivities of the firebrick, insulating brick and the
building brick are 1.4, 0.2, and 0.7 W jm.K respectively. Neglecting
radiation, calculate the rate of heat loss per unit wall surface area, and
the temperature of the outside wall surface of the furnace

A 80.0-kg student climbs up a tree. The gravitational potential energy of the student at this point is 2.00 x 10(3) J. How high is the student above ground?

a scientist uses a gamma degree scale for measuring temperature . in this scale water melts at 10° and boils at 130°. the scientist measures the temperature at which sodium melts to be 127°. express this in kelvin

Andy wants to measure the internal resistance of a 9V battery. When he connects the battery directly to a voltmeter, the meter measure 9.0V. When he connects the battery with a 10ohm resistor and use a voltmeter to measure the voltage across the resistor, the meter measure 8.5V. What is the resistance of the internal resistor? What are current going through the battery in both situations? How would you connect the ammeter in order to measure the current going through the internal resistor?