Thermodynamics ice cube question

In summary, the energy required to change a 40g ice cube from ice at -8 to steam at 108 degrees celcius is 18.27 Joules.
  • #1
physics_geek
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Homework Statement


How much energy is required to change a 40.0 g ice cube from ice at -8.0°C to steam at 108°C?


Homework Equations


q=mct


The Attempt at a Solution


i remember one of our TAs going over something like this a long time ago..I think i have to like add up all the energies from the ice going to like 0 C then to like 100C and then 108 C??

can someone help me out
 
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  • #2
  • #3
ok tell me if I am correct
add up all the energy from ice going from -8 to 0
0 to 100 and then 100 to 108?

am i even close?
 
  • #4
Yes, you are. Now you have to also consider the energy required to change phase (ice to water, water to steam).
 
  • #5
umm I am not sure what that means
 
  • #6
Consider: http://www.splung.com/heat/images/latentheat/phasechange.png and also the URL I gave you in my first post.

We separate this problem into stages:

Energy is required to raise the temperature of the solid, in this case the ice, from -8 to 0 degrees celcius. This is stage A-B.

Energy is then required to change phase from ice to water. At this point the temperature remains the same. This is stage B-C.

Once again, energy is required to raise the temperature from 0 to 100 degrees celcius. This is stage C-D.

The water then changes state again to steam. This is another phase change. This is stage D-E.

Finally, the temperature of the steam is raised by 8 degrees to 108 degrees celcius. This is stage E-F.

So, to calculate the energy required to raise 40g of ice from -8 to 108 degrees celcius we must use two equations. One to calculate the energy required to change phase at stages B-C and D-E, and another to calculate the energy required to raise the temperature at stages A-B, C-D and E-F.

The latent heat equation is:

[tex]Q=mL[/tex]

and the other equation required is the one you've already specified.
 

FAQ: Thermodynamics ice cube question

1. How does an ice cube melt?

When an ice cube is exposed to a temperature above its melting point, the molecules in the ice begin to gain energy and vibrate faster, causing the bonds between them to break. This results in the transformation of the solid ice into liquid water.

2. What is the role of thermodynamics in the melting of an ice cube?

Thermodynamics is the branch of science that deals with the transfer of heat and its effects on matter. In the case of an ice cube melting, thermodynamics helps us understand the transfer of heat from the surroundings to the ice cube, which causes it to melt.

3. Why does an ice cube melt faster in hot water compared to cold water?

This is because hot water has a higher temperature than cold water, which means it has more energy. When the ice cube is placed in hot water, the transfer of heat from the water to the ice cube is faster, causing it to melt quicker.

4. Can an ice cube melt without any external heat source?

Yes, an ice cube can melt without any external heat source if it is placed in a room with a temperature above its melting point. This is because the surrounding air molecules have enough energy to transfer to the ice cube and cause it to melt.

5. How does the size and shape of an ice cube affect its melting rate?

The surface area of an ice cube plays a significant role in its melting rate. Smaller ice cubes have a larger surface area to volume ratio, which means they melt faster than larger ice cubes. The shape of the ice cube can also affect the rate of melting, with thinner and flatter shapes melting quicker than thicker and taller shapes.

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