Register to reply

Isothermal and reversible expansion work problem (Physical Chem)

by LakeMountD
Tags: chem, expansion, isothermal, physical, reversible, work
Share this thread:
LakeMountD
#1
Sep20-07, 06:34 PM
P: 59
1. The problem statement, all variables and given/known data
A sample of 2.00 mol. CH3OH (g) is condensed isothermally and reversibly to liquid at 64*C. The standard enthalpy of condensation of methanol @ 64*C is -35.3 kJ/mol. Find w and q for the reaction.


2. Relevant equations
w = -nRT * ln(Vf/Vi) (although I don't have volume so I don't know how to find it)


3. The attempt at a solution

Honestly I can't find any other reversible/isothermal condition work formulas to use. I am sure I am just missing how to calculate volume here. I have n, R, and T but am not given V. Not sure if this can be calculated?
Phys.Org News Partner Science news on Phys.org
Sapphire talk enlivens guesswork over iPhone 6
Geneticists offer clues to better rice, tomato crops
UConn makes 3-D copies of antique instrument parts
chemisttree
#2
Sep21-07, 10:20 AM
Sci Advisor
HW Helper
PF Gold
chemisttree's Avatar
P: 3,724
What is the volume of 2 mol of methanol at 64C? Make an assumption about it's density and calculate it (I assume you know how to convert moles to mass). Same thing goes for the volume of 2 moles of gas (methanol before condensation). The ideal gas equation might not be completely accurate but it is a good place to start.
ace_of_spades
#3
Sep24-07, 05:28 PM
P: 1
Well, I am stuck on the same problem. I don't think that the ideal gas expression is the correct one.... also, what do you get if you do 64 kJ/mol * 2 mol ? (I think this is the enthalpy for the reaction). And then, should you go back to the Van der waals equation for the real gas and implement that in your calculation of work ?


Register to reply

Related Discussions
Reversible isothermal process Introductory Physics Homework 1
Physical Chem, work of a non-ideal gas Biology, Chemistry & Other Homework 1
Isothermal expansion hw problem Introductory Physics Homework 7
Reversible expansion Advanced Physics Homework 1
Isothermal expansion ! Engineering, Comp Sci, & Technology Homework 2