What will happen when a large amount of water at 0C....

In summary: Some water left over?In summary, when a large amount of water is mixed with ice at 0 degrees Celsius, equilibrium will be reached at an intermediate temperature between -10 and 0 degrees Celsius.
  • #1
Joe brewer
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0

Homework Statement


What will happen when a large amount of water at 0 C is mixed with ice at - 20 C? Assume ideal conditions.

Homework Equations


N/A

The Attempt at a Solution


I think the ice will rise in temp (without melting) but no new ice will be formed. Is this right?
 
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  • #3
Oh so there will be more ice formed but it will equilibrate at a temp between - 20 C and 0 C. Is that right?
 
  • #5
jedishrfu said:
What do you think and why?

Well I think that the ice can't melt, but the temp must equilibrate. So the heat will flow from the water to the ice. This will form more ice and raise the temp of the new ice until equilibrium is reached. Better?
 
  • #6
What will happen when a large amount of water at 0 C is mixed with ice at - 10 C?
 
  • #7
Mister T said:
What will happen when a large amount of water at 0 C is mixed with ice at - 10 C?

The same thing except it would equilibrate at a higher temp (still below zero). Probably less ice formed as well. Am I on the right track here?

Edit: or if there is enough ice, All of the water would turn to ice in both cases because all the water has to decrease in temperature. Since the L_f of water is fairly low, you would either have enough heat in the water to bring all of the ice up to nearly 0C without any phase change or all of the water would freeze at slightly below 0C as well. This would depend on the proportion between water and ice. Is that right?
 
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  • #8
Joe brewer said:
The same thing except it would equilibrate at a higher temp (still below zero). Probably less ice formed as well. Am I on the right track here?

What if the ice were at a temperature of -5° C?

Edit: or if there is enough ice, All of the water would turn to ice in both cases because all the water has to decrease in temperature.

That's why there's a "large" amount of water. How large? Large enough to keep at least some of it in the liquid state.

By the way, what's the significance of the special temperature of 0° C? If you had a 50/50 mixture of ice/water at that temperature and you transferred a small amount of heat energy to the mixture what would happen to it?
 
  • #9
0C is when any amount of water and ice would be at equilibrium.

At -5 C presumably the ice would increase in temp and some of the water would freeze.
 
  • #10
So ice at -20 °C will warm up.

Ice at -10 °C will warm up.

Ice at -5 °C will warm up.

Do you see where this is going?
 
  • #11
Yep! Basically as long as the ice is below zero, equilibrium will be at an intermediate temperature and will have x amount of additional ice.
 
  • #12
You've already told us this ...

0C is when any amount of water and ice would be at equilibrium.
 
  • #13
Joe brewer said:
Yep! Basically as long as the ice is below zero, equilibrium will be at an intermediate temperature and will have x amount of additional ice.
What would happen if the intermediate temperature happened to be - 10 degrees. How would it know to stop at - 10 degrees? You just told us that if you have ice at - 10 degrees in water at 0 degrees, the ice would heat up and more ice would form, and the ice would reach another intermediate temperature somewhere between -10 and 0. What if the new intermediate temperature happened to be - 5 degrees. How would it know to stop at - 5 degrees?

Chet
 
  • #14
So it would all turn to ice no matter what?
 
  • #15
Joe brewer said:
So it would all turn to ice no matter what?
No. There would be ice and water left in the end, but the final temperature would be ?
 
  • #16
Chestermiller said:
No. There would be ice and water left in the end, but the final temperature would be ?
Well, I was thinking somewhere between zero and the temp of the ice. Would it always be zero but the amount of ice would just increase? That's the only way I can think of that allows any water to be left over.
 
  • #17
Joe brewer said:
Well, I was thinking somewhere between zero and the temp of the ice. Would it always be zero but the amount of ice would just increase? That's the only way I can think of that allows any water to be left over.

That's the only equilibrium temperature at which a mixture of ice and water can exist. So looking at the way the problem is stated, the reference to a "large" amount of water is a hint that the author intends it to be a sufficient amount so that there is still some liquid water left in the container. As long is there is still some liquid, and some solid, and it's in equilibrium, there is only one possible thermometer reading.
 
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  • #18
Joe brewer said:
Well, I was thinking somewhere between zero and the temp of the ice. Would it always be zero but the amount of ice would just increase? That's the only way I can think of that allows any water to be left over.
Why do you feel this way? If you had ice floating in ice water inside an insulated container at 0C, do you feel like all the water would turn to ice. Where would all the heat given off when the water turned to ice go to? You are aware that, in order for water to turn to ice at 0 C, you need to remove the heat of freezing, correct?

Chet
 
  • #19
Let me walk you through what I'm thinking
1.ice is added
2.water gives up heat to ice, heating it up and turning into ice (still at 0c)
3.this continues until all the ice(old and new) is at 0c
4.water is still at 0c

On another note, Is this how (re) crystallization works?
 
  • #20
You got it.

This is how freezing works. I'm not sure what you mean about crystallization.
.
 
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  • #21
Joe brewer said:
Let me walk you through what I'm thinking
1.ice is added
2.water gives up heat to ice, heating it up and turning into ice (still at 0c)
3.this continues until all the ice(old and new) is at 0c
4.water is still at 0c

On another note, Is this how (re) crystallization works?
What recrystallization? After step 4, you have ice at 0 C sitting in a pool of ice water at 0 C. Game over. Nothing more happens. The system is now at equilibrium. To get more water to freeze, you would have to physically remove heat from the system.

Chet
 

1. What will happen when a large amount of water at 0C is heated?

When a large amount of water at 0C is heated, it will start to absorb heat energy and its temperature will increase. As the temperature of the water rises above 0C, it will begin to turn into liquid and eventually reach its boiling point of 100C.

2. Will the water at 0C freeze if left in a cold environment?

Yes, if the water is left in a cold environment, its temperature will continue to decrease until it reaches 0C. At this point, the water will start to freeze and turn into ice. The freezing point of water is 0C.

3. What happens to the density of water at 0C when it is heated?

As the temperature of water at 0C is heated, its density decreases. This is because the water molecules start to gain energy and move further apart, making the water less compact. This is why ice floats on top of liquid water, as it has a lower density than liquid water.

4. Can water at 0C exist in a liquid state?

No, water at 0C cannot exist in a liquid state. It will either be frozen into ice or turned into vapor as it reaches its boiling point. The only way for water to exist in a liquid state at 0C is if it is under high pressure, such as in deep ocean environments.

5. What happens if a large amount of water at 0C is mixed with a large amount of water at 100C?

If a large amount of water at 0C is mixed with a large amount of water at 100C, the resulting temperature will be somewhere in between the two temperatures. The final temperature will depend on the amount of water at each temperature and their specific heat capacities. This process is known as thermal equilibrium, where heat energy is transferred until the temperatures of the two substances are equal.

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