?The protein lysozyme unfolds at a transition temperature of \(75.5^{\circ} \mathrm{C}\)

Chapter 3, Problem P3B.9

(choose chapter or problem)

The protein lysozyme unfolds at a transition temperature of \(75.5^{\circ} \mathrm{C}\) and the standard enthalpy of transition is 509 \(\mathrm{kJ} \ \mathrm{mol}^{-1}\). Calculate the entropy of unfolding of lysozyme at \(25.0^{\circ} \mathrm{C}\), given that the difference in the molar constant-pressure heat capacities upon unfolding is \(6.28 \ \mathrm{kJ} \ \mathrm{K}^{-1} \mathrm{mol}^{-1}\) and can be assumed to be independent of temperature. (Hint: Imagine that the transition at \(25.0^{\circ} \mathrm{C}\) occurs in three steps: (i) heating of the folded protein from \(25.0^{\circ} \mathrm{C}\) to the transition temperature, (ii) unfolding at the transition temperature, and (iii) cooling of the unfolded protein to \(25.0^{\circ} \mathrm{C}\). Because the entropy is a state function, the entropy change at \(25.0^{\circ} \mathrm{C}\) is equal to the sum of the entropy changes of the steps.)

Text Transcription:

75.5 degree C

25.0 degree C

25.0 degree C

25.0 degree C

25.0 degree C

25.0 degree C

6.28 kJ K^−1 mol^−1