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Two Fairly Basic Thermodynamics Questions

  • #1
Please help! I need these done by wednesday and for the life of me i cannot seem to get the correct answer.

Homework Statement


How much ice must melt at 0 deg. C to gain 5 g of mass?


Homework Equations


I cannot seem to find many equations that relate thermodynamics and mass, maybe that is my biggest problem... The only one i could find was
Q=Lm


The Attempt at a Solution


I know the latent heat of fusion, but i do not know Q. I tried dividing both sides by L, giving me Q/L=m, but i wasn't sure where to go from there.




Homework Statement


Calculate the entropy change in isotermal transformation of ideal gas at the temperature of 27.5 deg. C if work done by the gas is 3.5 J.


Homework Equations


s(b)-s(a)=Cv*ln(Tb/Ta)+nR*ln(Vb/Va)
pV=nRT
dW=pdV


The Attempt at a Solution


since Tb/Ta=1, Cv*ln(Tb/Ta) is reduced to zero, leaving us with
s(b)-s(a)=nR*ln(Vb/Va)
i then attempted to use the ideal gas law combined with dW=pdV but i found myself running in circles trying to figure out what to do with p and n and trying to find Vb and Va at the same time.
 

Answers and Replies

  • #2
anyone? please this is very important and it is due at 12:00 midnight. i've tried really hard and i will continue to try but if anyone can set me in the right direction i will greatly appreciate it
 

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