Why Is the Delta G Positive in Hydrophobic Interaction with Water?

In summary, the conversation discusses the interaction between oil and water and the confusion surrounding the change in free energy and enthalpy. It is stated that oil and water do not readily interact together, with water aggregating in a more ordered state around the oil. The main point of confusion is whether the change in free energy and enthalpy are positive or negative, with some confusion about the exothermic nature of the reaction. The conversation ends with a question about the separation of oil and water, which happens spontaneously and results in a decrease in Gibbs free energy.
  • #1
lha08
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Homework Statement


So like let's say oil and water are interacting together. I know that they do not readily interact together and so water aggregates in a more ordered state around the oil.
But then this is where I'm confused;
-They say that the delta G (change in free energy) is positive, so that means free energy is required. Do they mean the energy is required to make the water molecules into a more ordered state?
-Then they apparently the delta H (change in enthalpy) is negative, because the reaction is exothermic...like I am confused...if the free energy is positive and requires free energy, wouldn't the delta H be positive indicating an endothermic reaction?


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The Attempt at a Solution

 
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  • #2
Who says that [itex]\Delta G>0[/itex] when an oil-water mixture separates? It happens spontaneously, so the Gibbs free energy must decrease.
 

FAQ: Why Is the Delta G Positive in Hydrophobic Interaction with Water?

What is hydrophobic interaction with water?

Hydrophobic interaction with water is a phenomenon in which non-polar molecules or groups within a molecule are repelled by water molecules and tend to aggregate together. This is due to the fact that water molecules are polar, and therefore, do not interact well with non-polar molecules.

How does hydrophobic interaction affect biological systems?

In biological systems, hydrophobic interactions play an important role in protein folding, membrane formation, and the binding of molecules such as hormones and enzymes. These interactions help maintain the structure and function of biological molecules and are essential for life.

What is the difference between hydrophobic and hydrophilic interactions?

Hydrophobic interactions involve the repulsion of non-polar molecules by water, while hydrophilic interactions involve the attraction of polar molecules by water. Hydrophobic interactions are driven by the tendency of water to minimize its contact with non-polar substances, while hydrophilic interactions are driven by the ability of water to form hydrogen bonds with polar molecules.

How does temperature affect hydrophobic interaction with water?

The strength of hydrophobic interactions decreases with increasing temperature. This is because as temperature increases, water molecules have more kinetic energy, making them more likely to disrupt the hydrophobic interactions and allowing non-polar molecules to interact with water molecules.

Can hydrophobic interactions be manipulated?

Yes, hydrophobic interactions can be manipulated by altering the chemical properties of molecules. For example, adding polar groups to non-polar molecules can increase their solubility in water and decrease their tendency to aggregate through hydrophobic interactions. This is often done in drug design to improve the solubility and effectiveness of medications.

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