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3 marksThe Kinetic Theory of Gases

CAPE Physics Unit 1 · 2019 · Paper 2 · Question 3(d)(ii)

A monatomic ideal gas in an engine goes through a cycle with four stages, as shown in Table 3. The quantity of gas is 0.0052 moles. At Stage A, the gas has a pressure of 6.0 × 10⁵ Pa and a volume of 5.0 × 10⁻⁵ m³. The gas is heated at constant volume to Stage B, where its temperature increases to 800 K. The gas then undergoes an adiabatic expansion, doing 37 J of work, until its pressure is 8.6 × 10⁵ Pa and its volume is 7.0 × 10⁻⁵ m³ at Stage C. At Stage D, the pressure is 6.0 × 10⁵ Pa and the volume is 7.0 × 10⁻⁵ m³.

Calculate the initial temperature of the gas (Stage A).

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Other parts of this question

  1. 3(a)On the grid provided in Figure 4 on page 19, plot the calibration curve (emf vs temperature) for the thermocouple. Draw the line of best fit through the points.[4 marks]
  2. 3(b)(i)Using the calibration curve plotted in (a), determine the temperatures when the thermocouple reads 51.0 mV.[1 mark]
  3. 3(b)(ii)With reference to the answer in (b)(i) and the calibration curve plotted in (a), state why this thermocouple is NOT the best option for use as a thermometer.[1 mark]
  4. 3(c)State TWO advantages of a thermocouple and give TWO corresponding situations where it will be the best choice of thermometer.[4 marks]
  5. 3(d)(i)Using the information given in Table 3 on page 20, sketch a P-V graph of the gas engine cycle, clearly labelling EACH stage and its corresponding pressure and…[4 marks]
  6. 3(d)(iii)Determine the heat energy supplied to the gas in going from Stage A to Stage B.[3 marks]
  7. 3(e)Define the internal energy of a gas.[1 mark]
  8. 3(f)State the first law of thermodynamics, clearly defining EACH term.[4 marks]
  9. 3(g)With reference to the first law of thermodynamics, calculate the change in internal energy of the gas in the engine as it goes from Stage B to Stage C.[2 marks]
  10. 3(h)State what happens to the volume, temperature and pressure of the gas in this process.[3 marks]

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