Short Quizzes

2013 Fall

August 29

1. Write the 1st Law in Equation form.
Ans:
DU = q - w
2. Circle the variables that are path functions T, P, q, w, U V.
Ans: q, w

August 30

1. Write the definitions of Cp and Cv.
Ans: Cp = (dq/dt)p, Cv =(dq/dT)v

2. What does reversible mean?
Ans: A process from state A to state B is said to have been conducted reversibly if it could be returned to state A leaving no more than a vanishingly small change in the surroundings.

Sept 4

How much work is required to isothermally compress an ideal gas at 300K and 1 atm to 10 atm?
Ans: dw = PdV = nRT dV/V; w = nRTln(V2/V1) but V2/V1 = P1/P2; w = 1 mole*8.31 J/(mol*K)*300Kln(1/10)

Sept 5

Three moles of ideal monatomic gas at 300 K are adiabatically compressed to one tenth their original volume. What is the final temperature?
Ans: T2/T1 = (V1/V2)^(R/cv) = (V1/0.1V1)^(R/1.5R) =10^0.667; T2 = 300 K * 10^0.667; Note: independent of moles.

Sept 6

How much work is required to adiabatically compress an ideal monatomic gas at 1 atm and 300 K to 1000 K?
Ans:
DU = 0 - w, w = -ncvDT = -n(1.5R)(1000-300)K; per mole w = -1050K*R; R= 8.31 J/(mol*K)

Sept 9

A Carnot Cycle composed of __________________
Ans: two reversible adiabaticsintersecting two isothermals

Sept 11

What is the mathematical definition of efficiency for a Carnot heat engine?
Ans: e = w/qH = 1 + qL/qH = 1 - TL/TH

Sept 12

How much work would it take to pump 1000 BTUs of heat into a sink at 300 K from a sink at 290 K? Assume a frictionless, no-mechaical-loss heat pump.
Ans: |qL|/|qH| = TL/TH, |qL| = 1000 BTU * 290/300, so w = 1000*10/300 (conservation of energy: qL ) or 100/3 BTU

Sept 13

What is the definiton of the thermodynamic temperature scale?
Ans: TL/TH = |qL|/|qH|

Sept 16

What three ways to make a Carnot Cycle irreversible?
Ans:
1) Make the high temperature sink hotter than the gas along the high temperature path: TsH > TgH
2) Make the low temperature sink colder than the gas along the low temperature path: TsL < TgL
3) recover less than max work during th eisothermal gas expansion path: wA < wMax

Sept 18

What is the 3rd Law of Thermodynamics?
Ans: The entropy for a pure crystalline material at absolute zero is zero.

Sept 23

Write the Boltzman Equation for S. Describe each term.
Ans: S = klnW where k is Boltzman's Constant (r/Avogadro's NUmber) and W is th enumber of configurations.

Sept 25

Show how to calculate DS for the mixing of 8 moles of argon with 2 moles of neon?
Ans: DS = - R[0.8ln(0.8) + 0.2ln(0.2)]10 gmoles R= 8.3144 J/(K*gmole)

Sept 26

From what mathmatical properties are the following determined?
a) Other Thermo Relations Ans: The total differential
b) Maxwell Relations Ans: Thequality of exactness

Sept 30

1) Write the a) so-called "Other Thermodynamic Relations and b) The Maxwell Realtion that derives from dU = TdS - PdV
2) What is the criteria of equilibrium at a) dT = dV =0 and b) dT = dV= 0
Ans: 1a ) T = (dU/dS)v and -P = (dU/dV)s; 1b) (dT/dV)s = - dP/dS)v; 2a) dA<= -dw' (or 0 if only PdV work); dG <= -dw' (or 0 if only PdV work)

Oct 2

Write the Gibb's-Helmhotz Equation.

Oct 3

State the defination of the heat of formation.

Oct 9

What are the 3 kinds of heat (enthalpy)?

Oct 10

What is the defination of chemical potential?

Oct 16

Print out any table from thermo-calc.

Oct 16

Write the Clausius and Clausius-Clapeyron Equations.

Oct 17

Print out any table from thermo-calc.

Oct 18

Draw a calculation schematic to find rhw AFT for combustion of C with O2 preheated to 800.

Oct 21

How does one find a (T, P) point of equilibrium if ΔG°>0 for all T's but ΔV <0?

Oct 23

Label the location of the s, l, g phases.

Oct 24

Write the Big Six Equations.

Oct 25

What is the Keq for the reaction

ZnO(s) + C(s) = CO(g) + Zn (l)

Oct 31

Attendeance for 10/31: name test.

Nov 3

What are the units for a) fugacity b) Keq?

Nov 4

Plot the fugacity coefficient result from integrating (z-1)/Pr dPr on the class handout of f'/p versus Pr.

Nov 6