HW Sol#8

# HW Sol#8 - Chemistry 131 Fall 2007 Solutions to Homework No...

This preview shows pages 1–2. Sign up to view the full content.

Chemistry 131, Fall 2007 Solutions to Homework No. 8 Problem 1. See Levine, problem 9.33. (a) True. Since x i < 1 for each component i in solution and since ln x i < 0 when x i < 1, then Δ mix G = RT i n i ln x i < 0, at constant T and P (Levine eq. 9.44). (b) True. The formation of a solution is an irreversible process, for which Δ S univ > 0 (Levine eq. 3.39). Since Δ G = - Δ S univ /T at constant T and P (Levine eq. 4.21), then Δ mix G < 0 for the formation of any solution. (c) False. For an ideal solution, Δ mix H = 0 (Levine eq. 9.47) and Δ mix S = - R i n i ln x i (Levine eq. 9.46). Therefore, Δ mix S 6 = Δ mix H/T . (d) False. The condition for phase equilibrium (Levine eq. 4.88) pertains to each individual component i in the system, e.g., a solution, not to the system as a whole. Therefore, for equilibrium between a solution and its vapor, the chemical potential of each substance in the solution must equal (or be less than, if the substance is non-volatile) the chemical potential of the vapor of that substance. (e) False. The relation between x v i and x l i for an ideal solution is given by Raoult’s law, x v i P = x l i P * i (Levine eq. 9.52). Therefore, in general x v i 6 = x l i . (f) True (Levine eq. 9.55). Follows from V i = ± ∂μ i ∂P ² T,n j (Levine eq. 9.31) and from μ i = μ * i + RT ln x i (Levine eq. 9.41). Problem 3. See Levine, problem 9.40. V = X i n i V i (Levine eq. 9.16) = X i n i V * m ,i (Levine eq. 9.55) = X i V i (Levine eq. 1.4) = X i w i ρ i (Levine eq. 1.2) , w = X i w i , ρ = w V = i w i i w i i , where w i and w represent the masses of component i and of the whole solution, respectively. Note that equal masses of benzene and toluene are in used in this problem, so the last expression simpliﬁes to: ρ = 2 ³ X i 1 ρ i ! - 1 = 2 ´ (0 . 8790 g / cm 3 ) - 1 + (0 . 8668 g / cm 3 ) - 1 µ - 1 = 0 . 8729 g / cm 3 . Problem 5.

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 05/22/2008 for the course CHEM 131 taught by Professor Lindenberg during the Fall '08 term at UCSD.

### Page1 / 14

HW Sol#8 - Chemistry 131 Fall 2007 Solutions to Homework No...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online