Which of the following shows the correct changes in thermodynamic properties for a chemical reaction in which amino acids are linked to form a protein?
A) +ΔH, +ΔS, +ΔG
B) +ΔH, -ΔS, -ΔG
C) +ΔH, -ΔS, +ΔG
D) -ΔH, -ΔS, +ΔG
E) -ΔH, +ΔS, +ΔG
Answer: C
I know that dehydration is endergonic (+ΔG).
I have two questions:
Why is entropy decreasing? In the beginning of the reaction, we have two amino acids. By dehydration, we have at the end two molecules: the two amino acids together and the H2O molecule. The same number of particles before and after.
Why is enthalpy change positive? You made a bond between the two amino acids. That is exothermic.