joniaguis - 8-5-2009 at 02:32
Determine the entropy change at constant pressure when 75 grams of COMPOUND X (molecular weight 150) at 373K is heated to 493K given that:
latent heat of vaporisation is 10,500 cal per mole
Molar heat capacities:
For liquid Cp = 25cal/deg/mole
For vapour Cp = 11.5 + 6.2x10^-3 T + 3.9x10^-5 T^2
Boiling point is 463K
My answer is 18.209 cal/mol. Is it correct??
DJF90 - 8-5-2009 at 03:04
Using my answer from the other entropy calculation you requested before but changing the appropriate values you should get delS = 5.403 + 0.722 +
0.186 + 0.559 + 22.678 = 29.548
This is equal to the MOLAR entropy. You are only heating ( 75/150) moles = 0.5 moles
Therefore you have to half your answer. So the answer should be 14.777, assuming I've not made a crippling mistake.
Sorry I cant post a fully worked answer as before but I have a lot of revision to be doing before my prelims in 4 weeks :|
Siddy - 9-5-2009 at 23:41
Thermodynamics, not kinetics 
joniaguis - 10-5-2009 at 01:19
lol yeah thermodynamics, but the excitement to post a new thread, you know. haha
Nicodem - 11-5-2009 at 10:43
Joniaguis, this is the sixth thread about your homework that you scatter all over the forum. Homework questions are not particularly welcome at this
forum which is about amateur chemistry and not about your schooling. However, if instead of consulting a book or asking your teacher, you feel this
unstopping urge to ask here, then at least do so properly - in a single thread dedicated to your homework in the Beginnings section - and not all over
the forum.