Calculating Heat of Fusion for Ice Cube: Lab Experiment Results

In summary, the conversation revolves around an experiment where an ice cube is melted in water to find the heat of fusion. The suggested method of finding the heat of fusion using the equation Q = m * hf is questioned and the experiment is described in detail. The law of conservation of energy is also mentioned as a method to solve the problem and the importance of determining the heat capacity of the styrofoam cups is stressed. The possibility of the heat transferred to the styrofoam cup being negligible is also considered.
  • #1
Revengeance
22
0
So i did a lab were we melt an ice cube in water. So i have to find the heat of fusion for the ice cube. But i am not sure how to do that.

What i was thinking of doing is finding the energy released by temperature of the ice cube increasing, then make that value of q, equal to m*hf, when it is melting. So:

Q = m * hf

Q/ m = hf

would this be correct? if you want my data it is:

mass of ice cube = 22.82 g

temperature = -7 degrees celcius

and for specific heat capacity i used 2.10 joules/ gram * degrees celcius

i know the theoretical value is 333, but my teacher is saying that our value of hf needs to be different.
 
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  • #2
Please describe the experiment, so far there is not enough information to help you (I guess I know what you did, and if so what you suggested is wrong, but I prefer to be sure).

Can you describe - step by step - changes that occurred to the ice cube during the experiment? Where did the heat needed for these changes came from?
 
  • #3
Borek said:
Please describe the experiment, so far there is not enough information to help you (I guess I know what you did, and if so what you suggested is wrong, but I prefer to be sure).

Can you describe - step by step - changes that occurred to the ice cube during the experiment? Where did the heat needed for these changes came from?
so this is how the experiment went:

we took a styrofoam cup , weighed it, added water into the cup and weighed it again. We then recorded the temperature of the war which was 23 degrees celcius. We then put an ice cube into the styrofoam cup with the water and waited for it to melt, we then recorded the temperature of the water and melted ice cube and got 9 degrees celcius, we weighed the mass again. After our teacher told us that the temperature of the ice cube was 7 degrees celcius. Mass of Styrofoam cup = 3.56 g

Mass of Styrofoam cup + water = 145.78 g

Mass of Styrofoam cup + water + melted ice cube = 168.6 g

T1 = 23°c

T2 = 9° c

Tice = -7°c
 
  • #4
I hate to ask teh same question again and again, but sometimes I have no choice.

Borek said:
Can you describe - step by step - changes that occurred to the ice cube during the experiment? Where did the heat needed for these changes came from?
 
  • #5
Start with listing the events having heat transfer history and apply the law of conservation of energy to the sum of the thermal events. I suggest looking up and reviewing solving 'method of mixtures' type problems in closed systems. These studies are also called 'Coffee Cup Calorimeter type experiments. Thermodynamics sections of most college chemistry or physics texts have some great examples.
 
  • #6
Don't forget to determine the heat capacity of the styrofoam cups.
 
  • #7
Interesting proposition... but how do you measure the temperature change of the styrofoam cup? I would think it would be negligible compared to ΔT for water, but I'm always open to technique.
 
  • #8
James Pelezo said:
Interesting proposition... but how do you measure the temperature change of the styrofoam cup? I would think it would be negligible compared to ΔT for water, but I'm always open to technique.
I think what you mean is that the heat transferred to or from the styrofoam cup is negligible compared to the other heat effects in this system.
 
  • #9
Yes, Chet ... much better said. Thanks.
 

What is the heat of fusion?

The heat of fusion, also known as the enthalpy of fusion, is the amount of heat required to change a substance from solid to liquid at its melting point.

How is the heat of fusion measured?

The heat of fusion is measured in joules per gram (J/g) or calories per gram (cal/g).

Can the heat of fusion vary for different substances?

Yes, the heat of fusion can vary for different substances depending on their molecular structure and properties.

What is the relationship between heat of fusion and melting point?

The heat of fusion is directly proportional to the melting point of a substance. This means that the higher the melting point, the more heat is required to change the substance from solid to liquid.

How is the heat of fusion used in practical applications?

The heat of fusion is used in various practical applications such as refrigeration, cooking, and industrial processes. It is also an important factor in understanding the behavior of substances during phase changes.

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