# Reversibility of evaporating ice ball

• hunterbowl
In summary, the conversation discusses whether a process in which a ball of ice is thrown against a wall and evaporates is reversible. The proposed solution is to run the process in reverse to see if it makes sense, but it is determined that the reverse process would not occur spontaneously according to the second law of thermodynamics. Therefore, the process is considered irreversible.

## Homework Statement

A ball of ice is thrown against a wall with such as speed than the ball of ice evaporates. Is this process reversible?

## Homework Equations

if entropy doesn't change, process is reversible.

## The Attempt at a Solution

I'm pretty darn sure the answer is no, but I am looking for qualitative reasons as to why this is not reversible.

When my teacher went over reversibility, he said we should just run the process in (time) reverse and see if it makes sense.

This situation does not make sense to me in reverse; water vapor will not spontaneously condense and freeze into an ice-ball that has some velocity.

Can anyone offer a more concrete line of reasoning other than "this process doesn't make sense in reverse".

That's a fairly good qualitative description of irreversibility.

One that's a bit more quantitative, how did Clausius characterize about the second law of thermodynamics?

Since the forward process involves converting mechanical energy entirely into internal energy of the snow ball (ignoring any heating of the wall, air etc.), what would the reverse process involve? Following up on DH's suggestion, does the second law permit such a process to occur spontaneously?

AM

## 1. How does evaporating ice ball work?

Evaporation is the process by which a liquid turns into a gas. In the case of an ice ball, the ice is exposed to a warmer environment, causing the molecules to gain enough energy to break free from their solid state and become a gas.

## 2. Can an evaporating ice ball be reversed?

Yes, the process of evaporation is reversible. If the temperature of the environment decreases, the gas molecules will lose energy and turn back into a liquid, eventually reforming into an ice ball.

## 3. Is there a limit to how many times an ice ball can be evaporated and reversed?

Theoretically, there is no limit to the number of times an ice ball can be evaporated and reversed. However, each time the ice ball goes through this process, it may lose some of its mass, resulting in a smaller size.

## 4. What factors can affect the rate of evaporation for an ice ball?

The rate of evaporation for an ice ball can be affected by various factors such as temperature, humidity, air pressure, and surface area. Higher temperatures, lower humidity, and lower air pressure can all increase the rate of evaporation, while a larger surface area can lead to faster evaporation as well.

## 5. Can the reversibility of evaporating ice ball be used for practical purposes?

Yes, the process of evaporation and condensation is commonly used in refrigeration and air conditioning systems. In these systems, a refrigerant is evaporated and condensed repeatedly to cool the air. This process is also used in desalination plants to turn saltwater into freshwater.