Kinetic energy of water vs ice

In summary, the average kinetic energy of water at 0 °C is greater than the average kinetic energy of ice at 0 °C due to the addition of energy required to break the potential energy (bonds) when ice melts. A thermometer measures temperature based on kinetic energy, but when the latent heat of fusion is applied, the potential energy decreases. This potential energy is transferred into something else, such as the PE increase seen when breaking bonds.
  • #1
TT0
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Homework Statement


The average kinetic energy of water at 0 °C is __________ the average kinetic energy of ice at 0 °C.

Homework Equations

The Attempt at a Solution


I said that it is greater than because when ice melts, energy is added to break the potential energy (bonds). I also know that average kinetic energy is directly linked to temperature so if they are at the same temperature, the average kinetic energy should be the same. The thing that is confusing me is that when the latent heat of fusion is applied to the ice, it breaks the bonds so it releases the potential energy so shouldn't the kinetic energy of water be higher than ice?

Cheers!
 
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  • #2
TT0 said:
I said that it is greater than because when ice melts, energy is added to break the potential energy (bonds).
Isn't that adding potential energy?

When a thermometer measures temperature, what is it actually responding to?
 
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  • #3
It is responding to the kinetic energy, but when the latent heat of fusion is applied, doesn't it break the bonds so therefore the potential energy would decrease? I am pretty sure this is wrong but I don't understand why. For example I think water has a lot of potential energy in its bonds and this potential energy is lost when it turns into gas because the bonds are broken. The potential energy is transferred into something which I am not sure of. Please help, thanks!
 
  • #4
TT0 said:
It is responding to the kinetic energy, but when the latent heat of fusion is applied, doesn't it break the bonds so therefore the potential energy would decrease? I am pretty sure this is wrong but I don't understand why. For example I think water has a lot of potential energy in its bonds and this potential energy is lost when it turns into gas because the bonds are broken. The potential energy is transferred into something which I am not sure of. Please help, thanks!
You have the changes in PE backwards. To break a bond you have to inject energy, just as you have to supply energy to send a rocket up, overcoming the attraction of the earth. The PE increases.
 
  • #5
I see thanks!
 

Related to Kinetic energy of water vs ice

1. What is the difference between the kinetic energy of water and ice?

The kinetic energy of water and ice refers to the energy that these two states of matter possess due to their molecular motion. However, the difference lies in the speed of the molecules. In water, the molecules are moving faster, resulting in a higher kinetic energy, while in ice, the molecules are moving slower, resulting in a lower kinetic energy.

2. How does the kinetic energy of water and ice affect their physical properties?

The kinetic energy of water and ice directly affects their physical properties. Water, with its higher kinetic energy, is in a liquid state and has a lower density than ice. On the other hand, ice, with its lower kinetic energy, is in a solid state and has a higher density. This is because the molecules in water have more space to move around and are less tightly packed compared to molecules in ice.

3. Can the kinetic energy of water and ice be changed?

Yes, the kinetic energy of water and ice can be changed. This can be done by either adding or removing heat. Adding heat to ice will increase its kinetic energy, causing it to melt into water. Conversely, removing heat from water will decrease its kinetic energy, causing it to freeze into ice.

4. How does the kinetic energy of water and ice affect their melting and boiling points?

The kinetic energy of water and ice plays a crucial role in determining their melting and boiling points. As mentioned earlier, water has a higher kinetic energy than ice. This means that it requires more energy (heat) to break the bonds between water molecules and change its state from liquid to solid (melting point). Similarly, the higher kinetic energy of water also means that it has a higher boiling point than ice since it requires more energy to break the bonds between molecules and change its state from liquid to gas (boiling point).

5. How does the kinetic energy of water and ice affect their ability to do work?

The kinetic energy of water and ice affects their ability to do work in different ways. Water, with its higher kinetic energy, is more fluid and can easily flow, making it ideal for work involving movement, such as hydroelectricity. On the other hand, ice, with its lower kinetic energy, is more rigid and solid, making it better suited for work requiring stability and support, such as building structures.

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