Heat Exchange Help Please!

  • Thread starter sadifermi
  • Start date
  • #1
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I need help with a question. I think I have an answer, but don't know if it's right. It also doesn't add up to 0 if I plug in the final temperture into the equation. But I keep getting the same answer. Help please!

A 150 g piece of copper at 90°C is placed in 250 g of water at 20°C. Assume that no heat escapes into the surroundings. Find the final temperature of the mixture.

mass of copper: (0.150kg)
specific heat capacity: (390J/(kg°C))
temperture of copper: (t2-90°C)

mass of water: (0.250kg)
specific heat capacity: (4200J/(kg°C))
temperture of water: (t2-20°C))

equation: (mass of copper)(spec. heat cap.)(final temp - intial temp) + (mass of water)(spec. heat cap.)(final temp - initial temp) = 0

(0.150kg)(390J/(kg°C))(t2-90°C)+(0.250kg)(4200J/(kg°C))(t2-20°C))=0
1108.5t2=26265
t2 = 23.7°C
 

Answers and Replies

  • #2
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Heat Exchange of Copper and Water

Homework Statement



I need help with a question. I think I have an answer, but don't know if it's right. It also doesn't add up to 0 if I plug in the final temperture into the equation. But I keep getting the same answer. Help please!

A 150 g piece of copper at 90°C is placed in 250 g of water at 20°C. Assume that no heat escapes into the surroundings. Find the final temperature of the mixture.

mass of copper: (0.150kg)
specific heat capacity: (390J/(kg°C))
temperture of copper: (t2-90°C)

mass of water: (0.250kg)
specific heat capacity: (4200J/(kg°C))
temperture of water: (t2-20°C))

Homework Equations




equation: (mass of copper)(spec. heat cap.)(final temp - intial temp) + (mass of water)(spec. heat cap.)(final temp - initial temp) = 0

The Attempt at a Solution



(0.150kg)(390J/(kg°C))(t2-90°C)+(0.250kg)(4200J/(kg°C))(t2-20°C))=0
1108.5t2=26265
t2 = 23.7°C
 
  • #3
ehild
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Correct solution!


ehild
 
  • #4
haruspex
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t2 = 23.7°C
It's just rounding error. If you plug in 23.6942 you'll get something close to 0. But don't change your answer to that. 23.7 C is fine.
 
  • #5
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Thanks! I appreciate it and the speedy reply!
 

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