Question

Latent heat flux is the loss of heat by the surface of a body of water caused by evaporation. To determine the latent heat flux over the Atlantic Occan, onc would necd to know A. \(\Delta H_{\text {fusion }}\) of water. B. \(\Delta H_{\text {vaporization }}\) of water. C. \(\Delta H_{\text {sublimation }}\) of water. D. \(\Delta H_{\text {ionization }}\) of water.

Short answer

B. \(\Delta H_{\text{vaporization}}\) of water

Step-by-step solution

Understand Latent Heat Flux

Latent heat flux refers to the transfer of heat energy which is associated with phase changes of water. Specifically, it involves processes like evaporation, condensation, freezing, or melting involving heat transfer without a change in temperature.

Identify the Relevant Phase Change

Latent heat flux over the ocean involves evaporation, meaning liquid water transforms into water vapor. This process is characterized by the latent heat of vaporization.

Determine the Correct \( \Delta H \) Value

oindent The latent heat relevant to evaporation is the enthalpy of vaporization. Given the options, \( \Delta H_{\text {vaporization}} \) corresponds to latent heat of vaporization.

Key concepts

latent heat of vaporization

Latent heat of vaporization is the amount of heat energy required to transform a substance from its liquid state to its gaseous state without changing its temperature. For water, this means turning liquid water into water vapor. This concept is crucial when we discuss evaporation and condensation processes.

The term 'latent' denotes that this heat is 'hidden' because it doesn't cause a temperature change but instead drives the phase transformation. For water to evaporate, it needs to absorb a considerable amount of energy, which breaks the hydrogen bonds between water molecules.

To put it simply:

• Evaporation: Liquid to gas, requiring latent heat of vaporization.
• Condensation: Gas to liquid, releasing latent heat of vaporization.

Understanding this concept helps us explain weather patterns and why sweating cools the human body.

phase changes of water

Water undergoes multiple phase changes, which are transitions between solid, liquid, and gas states. Each of these transitions involves latent heat. The key phase changes for water include:

• Freezing: Liquid to solid.
• Melting: Solid to liquid.
• Evaporation: Liquid to gas.
• Condensation: Gas to liquid.
• Sublimation: Solid to gas without passing through a liquid state.

During each phase change, water absorbs or releases energy. For example, during evaporation, energy (heat) is absorbed, causing water molecules to move more vigorously and transition into vapor. Conversely, during condensation, water vapor releases energy and transitions back into liquid form.

These phase changes are fundamental in natural processes like the water cycle, which includes evaporation from oceans and lakes, condensation forming clouds, and precipitation as rain or snow.

enthalpy of vaporization

Enthalpy of vaporization, often denoted as \(\( \Delta H_{\text{vaporization}}\)\), is a specific type of latent heat. It quantifies the amount of energy required to convert one mole of a liquid into a gas at constant pressure. For water, this enthalpy is particularly high, reflective of the strong hydrogen bonds between water molecules.

In numerical terms, the enthalpy of vaporization for water at its boiling point (100°C) is approximately 40.79 kJ/mol. This energy input breaks the intermolecular forces holding the liquid together, enabling the phase transition to gas.

Here's a practical way to understand it: When you boil water on a stove, you're providing heat, which gets absorbed by water molecules. Once they have enough energy to overcome attractive forces, they escape into the air as steam. This transformation exemplifies the enthalpy of vaporization in action.

This concept is crucial in understanding climate dynamics, refrigeration, and even in biochemical processes like protein folding.