path functions and not state functions. Q4(b) [7.5 Marks] (i) Predict which substance in each of the following pairs has the higher entropy at \( 298 \mathrm{~K} \) and justify your answer. \( 1 \mathrm{~mol} \) of \( \mathrm{C}(\mathrm{s}) \) OR \( 1 \mathrm{~mol} \) of \( \mathrm{Ca}(\mathrm{CO})_{3}(\mathrm{~s}) \) \( 1 \mathrm{~mol} \) of \( \mathrm{LiCl}(\mathrm{aq}) \) OR \( 1 \mathrm{~mol} \) of \( \mathrm{LiCl}(\mathrm{s}) \) (ii) State the molecular statistical definition of entropy, and explain how this definition may be used to explain the Second Law of Thermodynamics. Q4(c) [5 Marks] The enthalpy of vaporisation of methanol is \( 35.27 \mathrm{~kJ} \mathrm{~mol}^{-1} \) at its normal boiling point of \( 64.1^{\circ} \mathrm{C} \). Calculate the following: (i) The entropy of vaporisation of methanol at this temperature, (ii) The entropy change of the surroundings.
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- For the second pair, LiCl(aq) would have a higher entropy than LiCl(s) because in the aqueous state, the ions are free to move around, leading to more possible microstates. (ii) The molecular statistical definition of entropy is the logarithm of the number of Show more…
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The standard molar entropy of methanol vapor, $\mathrm{CH}_{3} \mathrm{OH}(\mathrm{g}),$ is $239.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ (a) Calculate the entropy change for the vaporization of $1 \mathrm{~mol}$ methanol (use data from Table 16.1 or Appendix J). (b) Calculate the enthalpy of vaporization of methanol, assuming that $\Delta_{r} S^{\circ}$ doesn't depend on temperature and taking the boiling point of methanol to be $64.6^{\circ} \mathrm{C}$.
The standard molar entropy of methanol vapor, $\mathrm{CH}_{3} \mathrm{OH}(\mathrm{g})$, is $239.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1} .$ (a) Calculate the entropy change for the vaporization of $1 \mathrm{~mol}$ methanol (use data from Table $18.1$ or Appendix $J$. (b) Calculate the enthalpy of vaporization of methanol, assuming that $\Delta S^{\circ}$ doesn't depend on temperature and taking the boiling point of methanol to be $64.6^{\circ} \mathrm{C} .$
Which of the following is in the correct order of standard state entropy? I. Liquid water < gaseous water II. Liquid water < solid water III. NH3 < H2 a. I only b. II only c. III only d. I and II only e. I and III only Which of the following will have the greatest standard molar entropy (S°)? a. NH3(g) b. He(g) c. C(s, graphite) d. H2O(l) e. CaCO3(s) Indicate which of the following has the lowest standard molar entropy (S°). a. CH4(g) b. CH3CH2OH(l) c. H2O(s) d. Na(s) e. He(g) Indicate which of the following has the highest entropy at 298 K. a. 0.5 g of HCN b. 1 mol of HCN c. 2 kg of HCN d. 2 mol of HCN e. All of the above have the same entropy at 298 K.
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