MiscellaneousContributions by:

John L. Falconer & Will MedlinDepartment of Chemical and Biological Engineering

University of ColoradoBoulder, CO 80309-0424

Supported by the National Science Foundation

Consider the following exact differential:

Which of the following is incorrect?

A. TS

H

P

VP

H

S

PS

H

P

T

S

2

PS S

V

P

T

TV S

V

P

T

B.

C.

E.

PVSTH

D.

P T

S V

T P

S

GV

T

P T

V G

T P

P T

G G

T P

P T

V S

T P

Which Maxwell relationship can be derived from the fundamental property relationship:

A.

B.

C.

E.

TSPVG

D.

For this P-H diagram, which is the most likely behavior for a constant volume process at the critical volume?

P

H

A BC

D

E

Which of these derivatives is zero for an ideal gas?

A. 1, 3, & 6

B. 2, 3, & 6

C. 2 & 6

D. 4 & 6

E. 5 & 6

PT

H

TP

H

SP

H

PP

S

PT

S

TP

S

1) 2) 3)

4) 5) 6)

As the temperature of a subcritical gas decreases, the correction term in the second virial coefficient _________.

A. approaches zero

B. becomes increasingly positive

C. becomes increasingly negative

Which fluid do you expect to have the largest value of the “a” variable in the van der Waals EOS?

A. Water

B. Helium

C. Methane

D. Nitrogen

Assume you identified three roots using the Peng-Robinson equation of state. Which of the three roots represent the physical state of the system?

A. The liquid root because liquids have lower U

B. The vapor root because vapors have higher S

C. The middle root

D. Vapor and liquid coexist

E. Do not have enough information

Which of the following gases do you expect to have the largest value of “b” in the van der Waals EOS?

A. Helium

B. Oxygen

C. 2,3,5‐Trimethyloctane

D. Water

2

2

V

an

nbV

nRTP

This is an isotherm at 75°C. There are 3 roots for the cubic EOS at 2 bar. Which is correct about these roots?

A. Z3 > Z2 > Z1

B. Z1 > Z2 > Z3

C. Z1 = Z2 = Z3

D. Z1 = Z3, but cannot say anything about Z2

E. Depends on the gas, no general relation

xx

P

V

fvap = fliq

Z1 Z2 Z3

Psat

Fugacity

x

Why is the compressibility factor less than 1 at most conditions?

A. Attractive forces dominate

B. Repulsive forces dominate

C. Real molecules occupy volume

D. It is not less than 1 at most conditions

Van der Waals accounted for the interaction of molecules. Using any cubic equation of state, an increase in the parameter associated with the strength of the molecular interactions (with everything else constant) would __________ pressure.

A. increase

B. decrease

C. not affect

Comparing a radial distribution function for a square well fluid, how would g(r) change for an Leonard-Jones fluid?

A. The discontinuities at r = σ and r = 1.5 σ would be smoothed out

B. The value of g would be highest at r = 0

C. The value of g would go through a maximum at r = 1.5 σ

The radial distribution function shown below belongs to:

A. An ideal gas

B. A supercritical fluid

C. A liquid

D. A crystalline solid

1 2 3 4

5

10

15

05

g (

r)

distance (A)

Which will have the highest magnitude for the enthalpy departure function at 100oC?

A. Water at 2.0 bar

B. Water at 0.5 bar

C. Argon at 2.0 bar

D. Argon at 0.5 bar