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Topic: Heat transfer....  (Read 5759 times)

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hannah

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Heat transfer....
« on: April 20, 2006, 07:40:13 PM »
Uhh okay if you have different amounts of a solution and mix them how do you find the resulting temperature?

Specifically, if you have 30 g H2O at 40 degrees C and 100 g H2O at 70 degrees, what's the resulting temp??

Thanks...
hannah
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Offline Qazzian

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Re: Heat transfer....
« Reply #1 on: April 20, 2006, 09:40:51 PM »
For that, since it's the same type of liquid (water) in both, just take a weighted average of the temperatures.
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Offline mike

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Re: Heat transfer....
« Reply #2 on: April 20, 2006, 10:12:56 PM »
Thermometer ::)
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hannah

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Re: Heat transfer....
« Reply #3 on: April 20, 2006, 11:13:50 PM »
I sort of thought of that, but what if its two different liquids like water and ethanol if i spelled that right?
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Offline Borek

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Re: Heat transfer....
« Reply #4 on: April 21, 2006, 02:45:47 AM »
Heat balance.
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Offline xiankai

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Re: Heat transfer....
« Reply #5 on: April 21, 2006, 07:07:02 AM »
heat loss by a substance = heat gain by another substance, assuming no heat loss to surroundings and 100% efficiency

the formula for heat is q = m c dT

where m is mass, c is the specific heat capacity and dT is the temperature change
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hannah

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Re: Heat transfer....
« Reply #6 on: April 21, 2006, 08:39:14 AM »
Right but how do you do that with two unknowns? it doesn't give me Q or dT...
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Offline Borek

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Re: Heat transfer....
« Reply #7 on: April 21, 2006, 08:59:43 AM »
Q gained = Q lost, that takes care about first unknown.

Final temperature of both liquids is identical, that takes care of dT.
« Last Edit: April 21, 2006, 09:07:19 AM by Borek »
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Offline Donaldson Tan

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Re: Heat transfer....
« Reply #8 on: April 21, 2006, 02:58:45 PM »
Although there is 2 unknown (c and Tfinal), c cancels out because both "substances" are actually water and therefore have the same heat capacity.
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