Two Fairly Basic Thermodynamics Questions

AI Thread Summary
The discussion focuses on two thermodynamics problems: calculating the mass of ice that must melt to gain 5 g and determining the entropy change during an isothermal transformation of an ideal gas. For the first problem, the user is struggling to apply the latent heat of fusion equation, Q = Lm, and is unsure how to find Q. In the second problem, the user simplifies the entropy change equation but becomes confused when trying to relate pressure, volume, and the work done by the gas. Both questions highlight the user's need for guidance on applying thermodynamic principles effectively. Assistance is urgently requested as the deadline approaches.
jimmypoopins
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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.
 
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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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