exam2_sol

# exam2_sol - 1 Calculate H for the reaction C(diamond...

This preview shows pages 1–4. Sign up to view the full content.

1. Calculate H for the reaction C(diamond) C(graphite) at the following conditions: A. T=25 0 C, P = 1bar ( ) ( ) 1895 / ff H H gr H diamond J mol ∆= = B. T = 125 0 C, P = 1bar (125 ) (25 ) ( ( ) ( ))(125 25 ) 1653.6 / pp H C H C C graphite C diamond C C J mol + = C. T = 25 0 C, P = 2000 bar This is very similar to your problem 3B from HW3: 00 0 0 () ( ) ( ) ( ) ()( ) ( ) 1512 / gr diamond gr gr diamond diamond gr diamond HP H P H P H P V P P MM HP VP P H P P P Jm o l ρρ +− −− = + =− The thermodynamic properties of graphite and diamond at T = 25 0 C and P = 1 bar are given in the table below. Assume that the densities and the heat capacities of both materials are constant H f , J/mol p C , J K -1 mol -1 density, g/cm 3 C(graphite) 0 8.527 2.25 C(diamond) 1895 6.113 3.51

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2. 100 grams of ethanol (C 2 H 5 OH) are mixed with 100 grams of methanol (CH 3 OH) at T = 10 0 C and form an ideal solution. This is problem 2 from HW 4. A. Calculate G as a result of mixing 00 0 0 11 2 2 1 1 1 2 2 2 1 1 2 2 () ( l n ) ( l n ) ( l n l n ) G n n n n n RT x n RT x nn R T n x n x µµ µ ∆= + + = + + + −+ = + Here n 1 = 100g/46(g/mol)=2.174 mol n 2 = 100g/32(g/mol) = 3.125 mol x 1 = n 1 /(n 1 +n 2 ) = 0.41, x 2 = 1-x 1 = 0.59 so that G = -8440 J B. Calculate A See the solution of the homework problem: G= A = -8440J C. What is the change of the entropy of the surroundings as a result of this process? / surr SH T As we discussed in the class, H=0 in the case where ideal solution is formed, so 0 surr S
3.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 09/06/2009 for the course CH 353M taught by Professor Lim during the Spring '08 term at University of Texas.

### Page1 / 5

exam2_sol - 1 Calculate H for the reaction C(diamond...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online