Hard molar specific heat question?

  • #1

Homework Statement


At very low temperatures, the molar specific heat of many substances varies as the cube of the absolute temperature: C=k*(T^3/To^3),
which is sometimes called Debye's law. For rock salt, To= 281K and k= 1940 J/mol*K

Determine the heat needed to raise 2.40 mol of salt from 30.0K to 50.0K .



Homework Equations


I don't know if this equation applies to solid . Q=nC*ΔT


The Attempt at a Solution


I know ΔT is 20, it seems to me that the only unknown for this question is T.
I tried to plug in 30 OR 50 into T, but I got the wrong answer.
 

Answers and Replies

  • #2
Borek
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Q=nCΔT is OK, but to make things more difficult C is a function of temperature.
 
  • #3
Q=nCΔT is OK, but to make things more difficult C is a function of temperature.

Could you tell me how to get the C value for this question? I know C=k*(T^3/To^3) from the problem, it also gives me k and To value, but I don't know what is T value.
 
  • #4
Borek
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T is given in the problem and is not constant - it changes from 30 to 50 K. You need to integrate.
 
  • #5
T is given in the problem and is not constant - it changes from 30 to 50 K. You need to integrate.
It works!!!!!!I just need to integrate that C function, thank you!!!
 
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