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Dropping a heated steel ball into ice and water

The second part of the question I'm doing asks 'What will happen if you drop a 100g steel ball at temperature 100c into a mixture of ice and water?'

so far I have

Dropping a 100˚C steel ball into a mixture of 500g ice and 500ml water at 0˚C
The temperature of the water will not change as the steel ball doesn’t have enough heat energy to melt all of the ice and increase the temperature of the water. All of the energy will be used in turning the solid ice into liquid water. This is the same reason that boiling water doesn’t exceed 100˚C.

Latent heat of melting for ice = 3.35x105J/KG
Qice=(mice)(Lm)

(0.5)(3.35x105) = 167500J

It would take 167500J to melt 0.5kg of ice

Im a little stuck with where to go next with it
thanks
Original post by Navm1
The second part of the question I'm doing asks 'What will happen if you drop a 100g steel ball at temperature 100c into a mixture of ice and water?'

so far I have

Dropping a 100˚C steel ball into a mixture of 500g ice and 500ml water at 0˚C
The temperature of the water will not change as the steel ball doesn’t have enough heat energy to melt all of the ice and increase the temperature of the water. All of the energy will be used in turning the solid ice into liquid water. This is the same reason that boiling water doesn’t exceed 100˚C.

Latent heat of melting for ice = 3.35x105J/KG
Qice=(mice)(Lm)

(0.5)(3.35x105) = 167500J

It would take 167500J to melt 0.5kg of ice

Im a little stuck with where to go next with it
thanks


Welcome to TSR
We would prefer it if you posted the whole question.
Especially as this is the 2nd part.

You need to find the amount of energy lost by the ball when it cools to zero to know if all the ice melts, or not.
Reply 2
Original post by Stonebridge
Welcome to TSR
We would prefer it if you posted the whole question.
Especially as this is the 2nd part.

You need to find the amount of energy lost by the ball when it cools to zero to know if all the ice melts, or not.


Thank you. sure, this is the whole question


4. If a steel ball of mass 100g at a temperature 100˚C is dropped into 1 litre of water at 20˚C, what is the temperature rise? What would happen if it were dropped into a mixture of ice and water at 0˚C? (Give a quantitative result)

Heat lost by steel ball = Heat gained by water
mc∆T_steel=mc∆T_water
Specific heat capacity of steel is 420Jkg- 1K-1
Specific heat capacity of water is 4200Jkg- 1K-1
Mass of steel = 0.1kg
Mass of water = 1kg
Heat lost by steel ball
(0.1kg)(420Jkg- 1K-1)(100˚C - x˚C) = (1kg)(4200- 1K-1)(x˚C - 20˚C)
42(100-x) = 4200(x-20)
4200 42x = 4200x 84000
4200 + 84000 = 4242x
88200 = 4242x
88200/4242 = 20.79 ˚C
Tf 20.8 ˚C
(0.1)(420)(100-20.8)= 3326.4J
Heat lost by steel ball is 3326.4J
Heat gained by water
3326.4J = (1kg)(4200- 1K-1)(∆T)
∆T = 3326.4/(1)(4200)
∆T = 0.792 0.8˚C
The temperature of the water rises by 0.8˚C.


edit: i had a go with what you said

Q=mc∆T
(0.1)(420)(100-0) = 4200J
mice = Qsteel / Lm

= 4200/3.35x105

mice = 0.0125kg = 12.5g

so the ball only melts 12.5g of ice
(edited 9 years ago)
Where does it say that there is 500g ice and 500g water in the mixture?
You use these values in your 1st post but the 2nd post just says "a mixture"?
Is it meant to be an equal mixture?
Reply 4
thats the whole question i was given, there were no quantities of ice and water specified so i just made them up. I would have just explained that the temperature wont rise at all but then would it still be a quantitative answer?
Original post by Navm1
thats the whole question i was given, there were no quantities of ice and water specified so i just made them up. I would have just explained that the temperature wont rise at all but then would it still be a quantitative answer?



Obviously what happens quantitatively depends on the quantity of ice and water in the mixture. Without a mark scheme or wider context to the question (eg book chapter theory if from a book; exam spec if from an exam) then you have to point out that in a mixture the temperature starts at zero and that initially only the ice melts so the heat from the ball goes into melting the ice. Then when and if it all melts (depending on quantities) the resulting mass of water plus melted ice will absorb heat from the ball and rise in temperature as you calculated in part one. You could assume quantities, as you have, and do that calculation.
Reply 6
Original post by Stonebridge
Obviously what happens quantitatively depends on the quantity of ice and water in the mixture. Without a mark scheme or wider context to the question (eg book chapter theory if from a book; exam spec if from an exam) then you have to point out that in a mixture the temperature starts at zero and that initially only the ice melts so the heat from the ball goes into melting the ice. Then when and if it all melts (depending on quantities) the resulting mass of water plus melted ice will absorb heat from the ball and rise in temperature as you calculated in part one. You could assume quantities, as you have, and do that calculation.


I've had a couple of vague questions or questions that seem to have something missing on this access course so far but I checked with the teacher and he says the point is just to demonstrate that the temperature doesnt change before the ice is all gone. So if I do carry on assuming the quantities does

Dropping a 100g, 100˚C steel ball into a mixture of 500g ice and 500ml water at 0˚C

The temperature of the water will not change as the steel ball doesn’t have enough heat energy to melt all of the ice and increase the temperature of the water. All of the energy will be used in turning the solid ice into liquid water, only once all of the ice was melted would the heat energy start to raise the temperature of the water and melted ice.

Heat lost by steel ball = Heat gained by ice
Latent heat of melting for ice = 3.35x105J/KG
Q_ice=m_ice L_m
(0.5)(3.35x105) = 167500J
It would take 167500J to melt 0.5kg of ice

When the steel ball is dropped in the mixture and cools to 0˚C

Q=mc∆T
(0.1)(420)(100-0) = 4200J
mice = Qsteel / Lm = 4200/3.35x105

mice = 0.0125kg = 125g

Only 12.5g of ice would be melted when the steel ball is dropped into the mixture.


Thanks for the help
Original post by Navm1
I've had a couple of vague questions or questions that seem to have something missing on this access course so far but I checked with the teacher and he says the point is just to demonstrate that the temperature doesnt change before the ice is all gone. So if I do carry on assuming the quantities does

Dropping a 100g, 100˚C steel ball into a mixture of 500g ice and 500ml water at 0˚C

The temperature of the water will not change as the steel ball doesn’t have enough heat energy to melt all of the ice and increase the temperature of the water. All of the energy will be used in turning the solid ice into liquid water, only once all of the ice was melted would the heat energy start to raise the temperature of the water and melted ice.

Heat lost by steel ball = Heat gained by ice
Latent heat of melting for ice = 3.35x105J/KG
Q_ice=m_ice L_m
(0.5)(3.35x105) = 167500J
It would take 167500J to melt 0.5kg of ice

When the steel ball is dropped in the mixture and cools to 0˚C

Q=mc∆T
(0.1)(420)(100-0) = 4200J
mice = Qsteel / Lm = 4200/3.35x105

mice = 0.0125kg = 125g

Only 12.5g of ice would be melted when the steel ball is dropped into the mixture.


Thanks for the help


Personally I would be happy with that approach. You could say how much ice would be melted by the heat lost from the ball. You could say that if there was 500g ice then it wouldn't all melt.


Small mistake in bold above.
12.5g ice melted as correctly stated in last line but not in the one above.

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