What Determines Equilibrium in a Liquid-Vapor System?

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In summary, the molecules in a liquid and its vapor have equal potential energy and total energy at equilibrium, but their kinetic energy may differ. This is because intermolecular forces are stronger in liquids than in gases, leading to differences in kinetic energy.
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erisedk
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Homework Statement


A liquid is in equilibrium with its vapor at its boiling point. On an average, the molecules in the two phases have equal:
(A) inter-molecular forces
(B) potential energy
(C) total energy
(D) kinetic energy

Homework Equations

The Attempt at a Solution


I know (A) is wrong as intermolecular forces in liquids are much more than those in gases. However, I'm confused between (B) (C) and (D). I know in gases KE is directly proportional to temperature. I'm not really sure about anything beyond this.
 
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  • #2
Okay --- it's not KE. That leaves PE and TE; do you think TE might be related more to KE than PE? Or, less?
 
  • #3
Why isn't it KE? Shouldn't KE also be proportional to temperature in liquids?
And I don't know whether TE might be more related to KE or PE.
 

FAQ: What Determines Equilibrium in a Liquid-Vapor System?

What is liquid-vapor equilibrium?

Liquid-vapor equilibrium is the state at which the rate of evaporation of a liquid is equal to the rate of condensation of its vapor, resulting in a balance between the liquid and vapor phases. This happens when the vapor pressure of the liquid is equal to the surrounding atmospheric pressure.

What factors affect liquid-vapor equilibrium?

The factors that affect liquid-vapor equilibrium include temperature, pressure, and the nature of the substance (i.e. intermolecular forces). These factors determine the rate at which molecules escape from the liquid and enter the vapor phase, as well as the rate at which molecules in the vapor phase condense back into the liquid phase.

How is liquid-vapor equilibrium related to boiling and evaporation?

Boiling is the process in which a liquid changes into its vapor phase throughout the entire volume of the liquid, while evaporation is the process in which a liquid changes into its vapor phase only at the surface. Both boiling and evaporation occur when the rate of evaporation equals the rate of condensation, which is known as liquid-vapor equilibrium.

What is the role of phase diagrams in understanding liquid-vapor equilibrium?

Phase diagrams show the relationship between temperature, pressure, and the physical state of a substance. They can be used to predict the conditions at which liquid-vapor equilibrium will occur for a specific substance. By analyzing a phase diagram, scientists can determine the critical point, boiling point, and other important information about liquid-vapor equilibrium.

Why is liquid-vapor equilibrium important?

Understanding liquid-vapor equilibrium is important in many practical applications, such as in the design of distillation columns, chemical reactions, and refrigeration systems. It also plays a crucial role in atmospheric science, as it helps to explain phenomena such as the water cycle and the formation of clouds.

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