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Calorimetry- how do I know the final temperature?

by jumbogala
Tags: calorimetry, final, temperature
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jumbogala
#1
Feb27-08, 09:57 PM
P: 400
I am doing a lab in which I have to come up with my own procedure. The lab involves putting a hot metal into water, then using calorimetry calculations to find the mass of the metal. (The metal is hotter than the water).

What I don't understand is how you know when to stop taking the final temperature of the water + metal mixture. I would assume it's when the mixture has reached thermal equlibrium. But at that point won't the whole mixture lose heat to the surroundings because the calorimeter isn't perfect?

So how do I know when it's reached thermal equilibrium if it will always be losing heat to the surroundings?

Also on the list of materials, it says "reggae". Nothing in the dictionary besides reggae music. Any ideas?
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chemisttree
#2
Feb28-08, 05:30 PM
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Assume that the calorimeter is perfect. The water will initially be cold and slowly warm up until the temperature changes no more. What will be that temperature if you know the heat capacity of the water and the metal and their respective temperatures before the experiment?

The reggae is probably there as a joke... Turn on some music.
jumbogala
#3
Mar2-08, 05:02 PM
P: 400
After the temperature stops rising, it will start to fall, I guess. So the highest recorded temperature would be the final temperature... right? So you would have -mct = mct, solving for m. I think I get it, thanks!

Also our teacher wants us to include variables. I understand that controlled variables will be things like measuring the temperature of the water the same way each time, etc.

But since this is an experiment that deals with calculations, couldn't the manipulated variable be different each time? And I wouldn't think there would be a responding variable since the mass of the metal doesn't ever change.

Am I right about that or are there variables that I'm missing?


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