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Heat Exchange

rlc

128
1
1. Homework Statement
(c11p34) You pour 160.0 g of hot coffee at 75.0 oC into a 230.0- g glass cup at 24.0 oC. If they come to thermal equilibrium quickly, what is the final temperature (in oC, enter deg in asnwer box)? Assume no heat is lost to the surroundings.

2. Homework Equations
(I don't even know, I've seen so many.)

3. The Attempt at a Solution
I've attempted this problem a couple times with different formulas, but none have worked.
Can someone just tell me what equation to use, please?
 

BvU

Science Advisor
Homework Helper
12,482
2,798
Suppose the final temperature is Tf. Then the coffee has cooled off to that temperature and the cup has heated up. They tell you no heat is lost, so apparently it's to do with heat. Where did the heat from the coffee go and where did the heat for the cup come from ?
 

rlc

128
1
Thank you for replying! I actually tried another equation and found the correct answer:
(mass coffee)(Temp coffee-Tf)(4.18 J/gC)=(mass glass)(Tf-temp glass)(0.840 J/gC)
(160)(75-Tf)(4.18)=(230)(Tf-24)(0.840)
Tf=63.57 deg
 

BvU

Science Advisor
Homework Helper
12,482
2,798
It's what we call a heat balance. Heat given off = heat taken up. And you did well to include the cp.
 

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