Specific Heat

  • Thread starter metalmagik
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  • #1
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Homework Statement


Two liquids of equal mass, one at 50 degrees Celsius, and one at 20 degrees Celsius, have different specific heats. Suppose the colder liquid has the higher specific heat. If the two liquids are mixed together in an insulating container, the equilibrium temperature of the mixture will be:
(a) 35 degrees C
(b) greater than 35 degrees C
(c) less than 35 degrees C
(d) not enough information


Homework Equations


Q = mc(delta T) ?


The Attempt at a Solution


Now I know there's nothing to really calculate here, so after thinking about this question for about 10 minutes...I thought the answer was (c) less than 35 degrees Celsius. However, after talking to one of my classmates, he brought up the fact that Volume is not given. Then, I told him that volume should really have no bearing on specific heat capacities, since specific heat is defined as the amount of heat needed to change 1g of the substance 1 degree Celsius either higher or lower. So, right now I'm between (c) and (d). Does anyone have the right answer? I even tried googling this after spending all this time deliberating with myself, and with my classmate. Any help is greatly appreciated.
 

Answers and Replies

  • #2
mgb_phys
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I would say 'C', you know that the cooler liquid must 'win'. It needs more energy to heat by 1deg than the hotter liquid gives by cooling 1deg and so the final temperaturemust be on the cold side.
 
  • #3
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That's what I thought, I just wasn't sure if the ungiven volumes played a role. Thanks mgb_phys!
 
  • #4
epenguin
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I would say 'C', you know that the cooler liquid must 'win'. It needs more energy to heat by 1deg than the hotter liquid gives by cooling 1deg and so the final temperaturemust be on the cold side.

No - it doesn't take more energy to heat a gram of the cooler liquid by 1 deg. than a kilo of the hotter one gives by cooling 1 deg. !
 
  • #5
mgb_phys
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The question says that there are equal masses of the two liquids.
 
  • #6
epenguin
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The question says that there are equal masses of the two liquids.

Sorry :blushing:I got confused in hurry with another comment. Then mgb is right.
 

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