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Homework Help: Specific Heat of Nickel / Latent Heat of Fusion

  1. Aug 15, 2011 #1
    1. The problem statement, all variables and given/known data
    I've done 2 experiments, one was to find the specific heat of nickel and the other was to find the latent heat of fusion.
    For the nickel experiment, it involves heating the nickel in a test tube in a water bath, and then transferring the pellets to a Styrofoam cup.
    With the ice experiment, it involves crushing ice and adding it to water at 35 C until it reaches 5 C.
    There are questions about the errors and reducing them that I'm not sure about.

    2. Relevant equations
    For the nickel experiment:
    1. What was the greatest source of error in the experiment?
    2. Suggest ways of reducing the source of error.

    For the ice experiment:
    3. Determine the sources of error in the experiment.
    4. Suggest ways of reducing error.

    3. The attempt at a solution
    For 1. I think some of the hot water may have entered the calorimeter because when the experiment was conducted, there was water that condensed onto the inside of the test tube. So some of the hot water may have entered the calorimeter I think...I'm not sure :confused: I'm also not really sure if the Styrofoam cup may have absorbed some of the heat but when calculating, I took the cup to have zero specific heat.

    For 2: I'm not really sure about this. Would moving the test tube around in the water bath help to distribute the heat evenly? and maybe the thermometer should not touch the glass of the beaker either.

    For 3: Impurities in the ice might be one....and it was also assumed that initial temperature of the ice was zero.

    For question 4: I'm not really sure how these problems would be fixed.
  2. jcsd
  3. Aug 15, 2011 #2
    bringing my post up before going to bed
  4. Aug 15, 2011 #3
  5. Aug 15, 2011 #4

    I like Serena

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    Hi paperdoll! :smile:

    I don't quite understand your experiments.
    To measure the specific heat of nickle, you need to measure the mass of the nickle, the temperature before, the temperature after and the energy transferred.
    How did you apply and measure those?
  6. Aug 15, 2011 #5

    3.) the source of error in here is the ice that you put on the warm water. you need to put an ice that is free from water(i mean an ice that is not on going a change of state but in zero degree, i hope you undestand.) or droplets of water. because the melted ice or small droplets of water is not in a form of ice and undergone the phase change. all we need is a pure ice to lessen the error.

    4.) to reduce the error you must coat or wrap or i should say wipe the moisture of ice or droplets of ice to be able to put an ice that is pure not an ice that is melting or something like that.

    its up to you now.
  7. Aug 15, 2011 #6
    That makes sense! Because the ice is continuously melting right? so to reduce error we will need to keep drying up the ice so it's only the ice and not extra water we are adding.
  8. Aug 15, 2011 #7
    With the nickel experiment, I measured the mass of nickel by using a beaker, weighing that. Then i weighed the beaker again with the nickel inside and subtracted the difference. The initial temperature of the nickel was the temperature after heating the water bath around it to around 90 C. The final temperature was after the pellets were added to the Styrofoam cup with room temperature water. But I think one of the error was that its kind of diffcult to measure the AVERAGE temp of all the nickel pellet. and I also wasn't sure when to know when the final temperature of the water and nickel pellet in stryofoam cup was reached.
  9. Aug 16, 2011 #8

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    That leaves the question how the amount of energy was measured?

    And to find the sources of the errors you need to consider how reliable your measurements are, and in how far you're actually measuring what you want to measure.

    1. I think we can agree that the mass of the nickle should be pretty accurate.

    2. What would influence the measurement of the initial temperature?

    3. And the final temperature?
    Since we have to wait awhile for the temperature to drop and to level out, is there any opportunity that some of what we want to measure gets lost?

    4. As for the accuracy of the amount of energy, you first need to say how you measured it, and what you measured.

    5. Finally what happens when we transfer the nickle?
    What are possible reasons that what we want to measure (contained heat and temperature) gets lost?
  10. Aug 16, 2011 #9
    oh, maybe when transferring the nickel to the Styrofoam heat would of been lost to the environment... so to improve that you would need to transfer it quicker? The thermometer might also have the same hot water on it too...hmm the initial temperature would be influenced by the position of the thermometer in the test tube of nickel pellet. The water might also spalsh when putting the pellets in...so that decreases mass of the water.

    I was also thinking about the ice experiment. We had an woolly cotton insulator around the calorimeter. If the water spalshed on the insulator, would it affect the experiment outcome?
  11. Aug 16, 2011 #10

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    How do you transfer the nickle?
    If you'd use for instance metal pliers, you may loose some heat.

    How do you know the water in the Styrofoam cup has a homogeneous temperature?
    Can you do something to make it more homogeneous?
    Or can you compensate for not being homogeneous?

    The final temperature in the Styrofoam cup would at first be going up, when the water slowly heats up, and then down again, losing heat to the environment...

    Btw, I assume that the heat transferred is measured by taking the final temperature of the water in the Styrofoam cup. With the specific heat of water you can calculate the heat transferred. Is that right?
    Of course for that to work you need the mass of the water in the Styrofoam cup, and you shouldn't splash.
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