IB Physics HL B 4 4 Hl Entropy and Disorder Questions

Explain entropy and disorder in HL thermodynamics, comparing system and surroundings during melting, gas cycles, heat transfer and spontaneous change.

Exam points

Explain entropy as a measure related to microscopic disorder and the number of accessible particle arrangements.
Interpret entropy changes in thermodynamic processes using complete mark-scheme evidence.

[Maximum number: 2]

The p V diagram shows a heat engine cycle consisting of adiabatic, isothermal and isovolumetric parts. The working substance of the engine is an ideal gas.

Figure for Question IB Physics HL B 4 4 Hl Entropy and Disorder Questions question 1 — IB Physics HL

The following data are available:

\begin{aligned} & p_{\mathrm{A}}=5.00 \times 10^{5} \mathrm{~Pa} \\ & V_{\mathrm{A}}=2.00 \times 10^{-3} \mathrm{~m}^{3} \\ & T_{\mathrm{A}}=602 \mathrm{~K} \\ & p_{\mathrm{B}}=3.00 \times 10^{4} \mathrm{~Pa} \\ & p_{\mathrm{C}}=4.60 \times 10^{3} \mathrm{~Pa} \end{aligned}

Suggest, for the change $A \Rightarrow B$ , whether the entropy of the gas is increasing, decreasing or constant.

Increasing because thermal energy/heat is being provided to the gas « and temperature is constant, $\Delta S=\frac{\Delta Q}{T} \gg$

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IB Physics HL B 4 4 Hl Entropy and Disorder Questions question 1