1. Sodium dodecyl sulfate is a detergent with a charged hydrophilic sulfate head group and a 12 carbon hydrocarbon tail. In solid form it exists as a monomeric molecule but upon dissolving in water at room temperature (298 K) it assembles spontaneously (ΔG = -16.4 kJ/mol) into a higher ordered micelle with the structure shown below.
A. Measurements of this process at room temperature show an enthalpy of micelle formation (ΔH) of -1.42 kJ/mol. Calculate the entropy for this reaction. Is micelle formation accompanied by an increase or decrease in the disorder of the system? Explain your answer.
B. Micelle formation is a good example of what type of noncovalent interaction?
C. Micelle formation in the presence of 0.5 M NaCl results in a more negative ΔH value of -8.49 kJ/mol with no further change in entropy compared to micelle formation in water. Is micelle formation more energetically favored in water or 0.5 M NaCl? What noncovalent interaction could account for this change in enthalpy?