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Topic: Thermodynamics Question  (Read 4426 times)

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Offline sassychar

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Thermodynamics Question
« on: November 08, 2007, 10:04:39 PM »
I need help on one question:


A 50.0g sample of copper is heated to 96.2C and then placed in a calorimeter containing 75.0g of water at 19.6C. The specific heat capacity of copper is 0.20Jg/k and that of water is 4.18J g/k. Calculate the final temperature of the metal and water assuming that all of the heat is lost by the copper is gained by the water.

I came up with this (50.0)(0.20Jg/k)(x-96.2)=(74.0)(4.18Jg/k)(x-19.6)

but the equation doesnt' seem to work. someone help me please.

Offline Sev

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Re: Thermodynamics Question
« Reply #1 on: November 08, 2007, 10:22:13 PM »
Quote
I came up with this (50.0)(0.20Jg/k)(x-96.2)=(74.0)(4.18Jg/k)(x-19.6)

74g?

Offline sassychar

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Re: Thermodynamics Question
« Reply #2 on: November 08, 2007, 11:42:02 PM »
Quote
I came up with this (50.0)(0.20Jg/k)(x-96.2)=(75.0)(4.18Jg/k)(x-19.6)

74g?


i meant 75.


Offline Sev

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Re: Thermodynamics Question
« Reply #3 on: November 09, 2007, 12:03:11 AM »
Quote
I came up with this (50.0)(0.20Jg/k)(x-96.2)=(74.0)(4.18Jg/k)(x-19.6)

For delta T of copper, try using the positive value (i.e. 96.2-x).

Offline sassychar

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Re: Thermodynamics Question
« Reply #4 on: November 09, 2007, 01:38:52 AM »
i tried that but the answer is incorrect.

the answer is suppose to be 26 C...

is the method even right?

Offline Borek

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Re: Thermodynamics Question
« Reply #5 on: November 09, 2007, 03:02:28 AM »
Method is OK (once you correct the delta T sign problem), but it seems to me like final temp is close to 22, not 26.
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