10. There are hydrogen bond donors (D), and acceptors (A). When the mixture (A+D) is transferred from water, designated as (w) to a nonpolar solvent (np), the free energy change (ΔG) of transfer is 6.12 kcal mol^-1 for the (A+D) mixture. A and D form a hydrogen bond in this nonpolar solvent and ΔG for this process is — 2.4 kcal mol^-1. When the hydrogen bonded molecule A-D is transferred from water to the nonpolar solvent ΔG for this process is 0.62 kcal mol^-1. The value of ΔG for the formation of hydrogen bond (A+B ←→A-B) in water is

    (1) -0.1 kcal mol^-1.
    (2) +3.1 kcal mol^-1.
    (3) -3.1 kcal mol^-1.
    (4) -1.78 kcal mol^-1.

The Impact of Solvent Environment on Hydrogen Bonding Free Energy

In chemistry and biology, hydrogen bonding is an essential interaction that is greatly impacted by the solvent environment. The stability and favourability of these interactions are determined by the free energy change (ΔG) of hydrogen bond formation.

Considering the Data and Interpretation

Given Data and Interpretation

1. ΔG of transferring A+D from water to a nonpolar solvent: +6.12 kcal mol⁻¹
2. ΔG of hydrogen bond formation in the nonpolar solvent: -2.4 kcal mol⁻¹
3. ΔG of transferring A-D (hydrogen-bonded) from water to the nonpolar solvent: +0.62 kcal mol⁻¹

Using the thermodynamic cycle, the ΔG for hydrogen bond formation in water is calculated as:

                     ΔG (H-bond in water) = ΔG (A+D → np) – ΔG (A-D → np) – ΔG (H-bond in np)

                            = (6.12 – 0.62 – 2.4) kcal mol⁻¹ = +3.1 kcal mol⁻¹

The right response is +3.1 kcal.

The Significance of This

Since water competes for hydrogen bonding, hydrogen bonds are more likely to form in nonpolar solvents.

Hydrogen bond formation is less favourable in water than in nonpolar solvents, as indicated by a positive ΔG in water (+3.1 kcal mol⁻¹).

This is significant because solvent effects affect binding affinities in protein folding, drug design, and biomolecular interactions.

Conclusion: In nonpolar solvents, hydrogen bonding is preferred.

Hydrogen bonds are less stable in water than in nonpolar environments, as indicated by the free energy change (ΔG) for hydrogen bond formation in water, which is +3.1 kcal mol⁻¹. This demonstrates how solvent interactions affect biological processes and molecular stability.