IBH Thermal Questions 1. A gas expands at a constant pressure of 5.4 atm from a volume of 3.6 L to a volume of

4.3 L. a) How much work does the gas do? 382.9J b) If the initial temperature of the gas was 312 K, find the final temperature. 372.7K

2. A monoatomic gas is kept at constant pressure 6.00x106 Pa, initial volume 0.200m3 and

temperature 300.0 K. If the gas expands at constant pressure to a volume 0.600m3 find a) The work done by the gas, 2.4x106J b) The temperature of the gas at the new volume 900K

3. A volume of 2.00L of a gas is heated from 20.0°C to 80.0°C at constant pressure. What is

the new volume? 2.41L 4. A sealed bottle contains air at 22.0°C and a pressure of 12.0 atm. If the temperature is

raised to 120.0°C what will the new pressure be? 15.6 atm 5. A gas is kept at a pressure of 4.00 atm and a temperature of 30.0°C. When the pressure

is reduced to 3.00 atm and the temperature raised to of 40.0°C the volume is measured to be 0.45 L. What was the original volume of the gas? 0.33L

6. An air bubble exhaled by a diver doubles in radius by the time it gets to the surface of the

water. Assuming that the air in the bubble stays constant in temperature, find by what factor the pressure of the bubble is reduced. By a factor of eight

7. 12.0 kg of helium are required to fill a bottle of volume 5.00L at a temperature of 20.0°C?

What pressure will the helium have? 1.46x109Pa 8. What mass of carbon dioxide is required to fill a tank of volume 12.0 L at a temperature of

20.0°C and a pressure of 4.00 atm? 87.9g 9. A flask of volume 300.0mL contains air at a pressure of 5.00x 105 Pa, and a temperature

of 27.0°C. If the flask loses molecules at a rate of 3.00x 1019per second, after how much time will the pressure in the flask be reduced to half its original value? (Assume that the temperature of the air remains constant during this time) 10.1 minutes

10. The diagram shows a cylinder in vacuum, which at the top has a movable, frictionless

piston. An ideal gas is kept in the cylinder. The piston is at a distance of 0.500m from the bottom of the cylinder and the volume of the cylinder is 0.050m3. The weight on top of the cylinder has a mass of 10.0 kg. The temperature of the gas is 19.0°C. a) What is the pressure of the gas? 1000 Pa b) How many molecules are there in the gas? 1.24x1022 c) If the temperature is increased to 152.0°C, what is the new

volume of the gas? 0.07m3 0.5m gas

11. The P-V diagram shows two isotherms for a fixed mass of ideal gas, at temperatures Tx and Ty. Which one of the following is correct?

a) Tx < Ty b) Tx > Ty c) Tx = Ty d) Temperatures cannot be compared from a P-V diagram alone.

12. A gas is taken through a cyclic process A> B > C > A as shown in the P-V diagram. The

work done by the gas during one complete cycle is

a) 24 kJ. b) 12 kJ. c) 6 kJ. d) 4 kJ

13. The energy absorbed by an ideal gas during an isothermal expansion is equal to

a) the work done by the gas. b) the work done on the gas. c) the change in the internal energy of the gas. d) zero.

14. When a gas is compressed adiabatically, the work done on the gas is

a) zero. b) less than the change in internal energy, but not zero. c) equal to the change in internal energy. d) greater than the change in internal energy.

15. When a gas in a thermally insulated cylinder is suddenly compressed, the change of state is a) adiabatic. b) isothermal. c) isobaric. d) isochoric.

16. The graph below shows the variation with volume of the pressure of a system.

The work done in compressing the gas from R to P is a) 5.0 x 105 J b) 4.5 x 105 J c) 3.0 x 105 J d) 0.

17. In one cycle of a heat engine, 300 J of energy is absorbed and 200 J of energy is

ejected. The efficiency of the engine is a) 3/2 b) 2/3 c) 1/2 d) 1/3

18. The diagram shows the variation with volume V of pressure p during one complete cycle

of a heat engine.

19. The work done is represented by the area a) A. b) B. c) (B + A). d) (B - A).

20. A gas expands rapidly. The process is approximately a) isobaric. b) isothermal. c) adiabatic. d) isovolumetric.

21. The diagram shows the pressure / volume (p/V) diagram for one cycle PQRS of an

engine. In which sections of the cycle is work done on the engine?

a) A.SP only b) B. PQ only c) C. SP and PQ only d) D. RS and SP only

22. The figure below represents the four stages of a Carnot Cycle.

Which of the following describes the process A>B? a) Isothermal expansion b) Isothermal compression c) Adiabatic expansion d) Adiabatic compression

23. The second law of thermodynamics states that the entropy of the universe is

a) increasing. b) decreasing. c) zero. d) constant but not zero

24. An ideal gas is enclosed in a cylinder fitted with a piston as shown below. The cylinder

walls are thermally conducting. The gas is compressed isothermally by pushing the piston in slowly.

For this process, the thermal energy exchanged with the surroundings will be a) zero. b) less than the work done. c) equal to the work done. d) greater than the work done.

25. A ships engineer proposes generating energy for ships by inventing an engine which would take in sea water, extract some of its internal thermal energy and use this for driving the ship. The resulting cooled water would then be returned to the sea. How do the first and second laws of thermodynamics relate to this proposed process? First law Second law a) A. Satisfied Violated b) B. Violated Violated c) C. Satisfied Satisfied d) D. Violated Satisfied.

26. The solid line on the graph below represents the pressure-volume changes for an ideal

gas undergoing an isothermal expansion. The dashed line on the graph shows the pressure-volume changes for an expansion that is not isothermal.

In the expansion that is not isothermal, the internal energy of the gas a) increases. b) decreases. c) stays the same. d) changes but whether it decreases or increases cannot be determined from the graph

alone. 27. An engine takes in an amount E of thermal energy and, as a result, does an amount W of

useful work. An amount H of thermal energy is ejected. The law of conservation of energy and the efficiency of the engine are given by which of the following?

28. Which of the following is the internal energy of a system? a) The total thermal energy gained by the system during melting and boiling. b) The sum of the potential and the kinetic energies of the particles of the system. c) The total external work done on the system during melting and boiling. d) The change in the potential energy of the system that occurs during melting and

boiling. 29. The graph below shows the variation with volume V of the pressure p of a gas during

one cycle of an engine.

During which operations, PQ, QR, RS and SP does the gas do external work? a) PQ only b) RS only c) QR and RS only d) PQ and RS only