# Test 2 Pchem

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 Author: ljdankov ID: 136363 Filename: Test 2 Pchem Updated: 2012-02-19 19:25:12 Tags: Physical chemistry Folders: Description: Chapter 3,4 Show Answers:

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1. Carnot efficiency
2. Entropy formula for adiabatic isothermal cycle (carnot)
• Energy over temperatrure
3. Is entropy a state function
Yes
4. Is Pressrua state function
Yes
5. Is Volume a state funciton
Yes
6. Is Temperature a state function
Yes
7. Is Internal Energy a state function
Yes
8. Is work a state function
No
9. Is enthalpy a state function
No
10. What do state functions equal in a carnot cycle
0
11. What is a clausius inequallity
Statement that entropy of an irreversible cycle is less than that of a reversible cycle.
12. What is always true of entropy of an irreversible cycle?
Alays less than 0
13. Clausius statement of entropy
The universal entropy always moves towards a maximum
14. Microscopic entropy deffinition
Entropy is a measure of disorder. The more ways molecules can move and be arranged, the higher the entropy
15. How does entropy affect temperature
Higher temperature leads to higher entropy
16. What is entropy of melting?
\
17. What is entropy change of boiling
18. What can always be said of the sign on entropy of a state change?
If state change is to more mobile form, is positive, if to less mobile form is negative.
19. Enthalpy of transition formula
\
20. Change in entropy at constant volume formula?
nRln
21. Change of entropy at constant volume formula
22. What is change in ewntropy formula when both temp and volume change
n
23. Entropy of mixing gas in terms of mol fractions?
-(n1+...+nn)R(x1ln(x1)+...+xnln(xn))
24. When is entropy 0 when mixing gasses?
When there is no change in volume
25. Entropy of mixing gasses in volume term formula?
26. Entropy phase change order of operations.
• 1) Heat or cool initial phase to temperature of phase change, calculate entropy
• 2) Calcualte entropy of phase changte
• 3) Heat or cool final phase to final temperature, calcuate entropy
• 4) sum entropies
27. Nernsts theorem
Entropy changes become zero at absolute zero
28. Absolute entropy of a reaction formula?
\si
29. WHat is the entropy condition of equilibrium and when will this occur? Two formulas and deffinition
dSTotal=dSsystem+dSSurroundings=0

• dq-Tds=0
• On a graph of entropy, we reach equilibrium when the composition of system is such to maximize entropy.
30. What can be said of relationship between entropy of surrounding and change of energy in system?
d
31. What must happen to entropy for a process to be spontaneous?
The overall entropy must increase.
32. What is Gibbs free energy in relation to entropy?
G= H-TS
33. What is gibbbs requirement for equilibrium at constant Temp and PRessure?
dG=0
34. Which direction will a reaction move as determined by gibbs?
In which ever direction minimizes gibbs free energy
35. Is Gibbs a state function?
Yes
36. What is the deffinition of helmholtz energy (A)?
U-TS
37. When will we reach equilibrium according to helmholtz?
When dA = dU-TdS = 0
38. What does a negative gibbs tell us a bout a reaction?
That it will happen spontaneously.
39. What is an exergonic compound?
One whose gibbs free energy is negative and will form spontaneously.
40. What is an endergonic compound
One whose gibbs free energy is Positive and will not form spontaneously.
41. Gibbs in terms of volume and pressure?
\tri
42. Internal energy change for process involving only PV work (Maxwell)?
du = -PdV + TdS
43. Fugacity
Measure of how far from ideality a gas is.
44. Relationship betweeen work and helmholtz (a)
\
45. Relationship between gibbs and work
\
46. What is the Equilibrium constant ( K)?
• If stoichometetric equation is:
• Products -> reactants
• aA+bB = cC + dD
• k=
47. How does equilibrium constant (k) related to gibbs?
48. What are the three equilibrium constants and what differentiates tehm?
• k0= dimensionless constant
• kp= dimensionless form of K if units are in pressure (bar)
• kc is the dimensoinless form if units are in concentration (mol/L)
49. What happens to reaction rates at equilibrium?
Forward and backward rates proceed at same rate.
50. What energy condition indicates equilibrium?
Gibbs and helmholtz are minimized.
51. Chemical Potential: Symbol, deffinition and Formula
• is the molar gibbs energy of a reaction at pressure other than 1 bar (not in standard state).
52. Gibbs energy chemical potential form when not at equilibrium
\t
53. What is \
Stoichometric constant.=
54. What be da formula for Kc ?
= {
55. What is relation between kp and kc ?
k
56. What is kx?
• Equilibrium constyant in mol fractions.
• l
57. What is Kp iun terms of Kx?
58. Molality?
Mols/Kg
59. Solubility product?
• ksp = [X]x[Y]y= axxayy
• Tells how much of a substance will dissolve.
60. What is a?
a is the shorthand for chemical activity in a sollution.
61. Heterogeneous equilibrium?
• This is when we have a reaction in which reactants are in different phase.
• We treat pure solids and liquids as having a concentration of 1 and an activity coefficient of 1. They thus drop out of K.
62. Mix of reactions.
If there be multiple reactions, then:

63. =
64. Van Hoft Equation for effect of temperature on equilibrium constant?
• This equation maps the effect of temperature on equilibrium constants.
• integrating this yeilds:
65. Temperature dependence of equilibrium constant for ideal gases?

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