I need an explanation for this Chemistry question to help me study. exam on physical chemistry. October 16th, Friday at 10:30 am CDT. The exam for 1hr. Once I send you the exam I can not text you during the exam time. Try to send me the answers for each question once you solve it so I can copy it.
Chem 3433, Physical Chemistry, Fall 2019, Exam #2 Name _____________________
Turn cell phones OFF! You may use notecard, ruler, calculator Write your name on the other side with the data table.
- 1.00 mol of Cu at 500 °C was placed in 200 g of water at 25.00 °C. This system was thermally insulated. A.) (10) What is the final temperature of the system? B) (15) What was ∆H for the Cu and for the water?
- (25 pts) True of False (if false, explain why)
- _______ ∆U is usually straightforward to measure in a bomb calorimeter.
- _______ If there are no phase changes, a plot of CP vs T can be integrated to yield the entropy change for a substance.
- _______ The entropy of all substances appear to extrapolate to 0 at 0 K.
- _______ The entropy change for boiling is roughly constant.
- _______ ∆S must be calculated over a reversible path.
- Liquid water, 36 g initially at 50 °C was put into a large freezer at -10°C. The water didn’t freeze until -10 °C (it was supercooled). A) (15 pts) What is ∆S for the water for this process? B) (10 pts) What is the total ∆S for the overall system and is the process spontaneous?
- (15 pts) One mol of an ideal monoatomic gas is expanded from 300 K and 10 bar to 350 K and 5 bar. Calculate ∆U, ∆H, and ∆S for this process. Is this a spontaneous process? (10 pts) Given S as a function of T and P, show that dS(T,P) = (CP/T) dT – (∂V/∂T)PdP
CV (monoatomic) = (3/2) R, CP (monoatomic) = (5/2) R,
R = 8.314 J/K/mol = 0.08205 L atm/K/mol
Cp (H2O, liquid) = 75.3 J/K mol, Cp (H2O, ice) = 37.2 J/K mol ∆Hf = 334 J/mol.
- (0 pts)
Who was the “Man in Black?” ______________________
Where was the California country music capital? ______________________
Some Possibly Useful Formulas
A. Taylor-McLauren Series
B. Useful Applications of A-1
C. Useful Integrals (x<0)
(for a > 0: n= 1,2,3, …) (C-4)
(for a > 0: n= 0,1,2,3, …) (C-5)
D. Other Series
E. Stirling’s Approximation
ln N! = N ln N – N (E-1)
1 atm = 1.013x 106 dyn/cm2 FDB 1/18
1 atm = 1.013x 105 Pa
F. Some Partial Derivative Manipulations
Reciprocal Rule (F-1)
= Chain Rule (F -2)
= Cyclic Rule (F -3)
= No-Name Rule (F -4)
G. Definitions of Major State Functions and Their Differentials
dU = TdS – PdV (G-1)
H = U + PV dH = TdS + VdP (G-2)
A = U – ST dA = -SdT – PdV (G-3)
G = U -ST + PV dG = -SdT + VdP (G-4)
H. First Derivatives of the Above Equations
= T = -P (H-1)
= T = V (H-2)
= -S = -P (H-3)
= -S = V (H-4)
I. Maxwell Relations (from second Derivatives)