Question

1. The hydrophobic effect drives the separation of oil and water, the formation of the lipid bilayers in water, and the folding of proteins incells. What are the values of delta G, delta H, and delta S in all of these processes? (Delta = change)

Answer 1

Thermodynamics of Hydrophobic Interactions

The system’s enthalpy change or the value of ?H may be negative, zero, or positive because the new hydrogen bond may completely, partially,or over compensate for the hydrogen bond break by the hydrophobic interaction. So value of ?H , is insignificant in determine the extemporaneity of the reaction ,when mix water and hydrophobic molecules because the value of (?S) or the change in entropy is large.

According to the  formula of Gibbs energy -

?G = ?H ? T?S

with value of ?H is a small unknown and a value of ?S is large negative, the ?G value will turn out to be positive.

If ?G value is positive it indicates that the mixing of the water and hydrophobic molecules is not spontaneous.

Formation of Hydrophobic Interactions-

The mixing water and hydrophobic molecules is not spontaneous, but hydrophobic interactions between hydrophobic molecules is spontaneous. When hydrophobic molecules come in contact to each other, the value of enthalpy increases so ?H is positive because some of hydrogen bonds will be broken which form the clathrate cage. Slitting down a portion of the clathrate cage would cause the value of entropy to increase so ?S is positive, since formation so it decreases the value of entropy.

According to the gibbs formula

• ?H = small positive value
• ?S = large positive value
• So ?G is negative and hence hydrophobic interactions are spontaneous.
  when No nteractiom Hydrophobic inuterachion > H Positive bS Positive △G= Negative Negative ositive