Solving Final Temperature of Copper-Water Mixture

Click For Summary

Homework Help Overview

The discussion revolves around a thermal equilibrium problem involving a copper-water mixture. The original poster attempts to find the final temperature of a mixture consisting of a 150 g piece of copper at 90°C and 250 g of water at 20°C, assuming no heat loss to the surroundings.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of the heat exchange equation, questioning the validity of the calculated final temperature and its implications on energy conservation. Some participants express concern over the results not summing to zero when substituted back into the equation.

Discussion Status

There is ongoing dialogue about the accuracy of the final temperature calculated by the original poster. Some participants suggest that rounding may be affecting the results, while others confirm that the answer provided is acceptable despite minor discrepancies.

Contextual Notes

Participants note the assumption of no heat loss to the surroundings, which is critical to the problem setup. There is also mention of potential rounding errors affecting the final temperature calculation.

sadifermi
Messages
5
Reaction score
0
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
 
Physics news on Phys.org
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
 


Correct solution!ehild
 
sadifermi said:
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.
 
Thanks! I appreciate it and the speedy reply!
 

Similar threads

Replies
12
Views
1K
Replies
2
Views
1K
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
2
Views
2K
  • · Replies 11 ·
Replies
11
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K