Exam 4 - Thermodynamics

Wed 11/30 7-9pm

Results




Average 49970: 74.55

Avegage 49975: 74.29

ALL Average: 74.43

Median: 76

Std Dev: 17.36

Total 100's: 23

bubblesheet errors: 11

What the Student Brings to Exams
  • official UT ID card (with your picture and name on it)
  • a simple scientific calculator (not a graphing calculator)
  • a pencil(s) and eraser
  • memorized formulas in your head - not on paper or anything else
  • nothing else is allowed
What we provide for the Exams
  • A printed copy of the exam (every exam has a unique version number on it).
  • An answer sheet for the exam. This is a bubblesheet for your answers.
  • An exam cover page that has ALL needed conversion factors and data. No formulas will be given.
  • A periodic table of the elements with symbols, atomic number, and atomic weights.
What Formulas the Student Should Memorize

For a nicer more annotated version of the formulas, click on smiley there šŸ™‚

ΔU = Uf - Ui

ΔU = q + w

q   =   m Cs ΔT

q   =   n Cm ΔT

q   =   m ΔHtrans

q   =   n ΔHtrans

w   =   -PextΔV

w   =   -ΔngasRT

Δngas = (#mol gas prod) - (#mol gas react)

H = U + PV

ΔH = ΔU + PΔV

ΔU = ΔH - PΔV

ΔU = ΔH - ΔnRT

ΔH = qP

ΔU = qV

q   =   nRT ln(V2/V1)

w   =  ā€“nRT ln(V2/V1)

qcal   =   -qsys

qcal   =   CcalΔT

qcal = mwater · Cs,water · ΔT + Chardware · ΔT

ΔHrxn = ΔH1 + ΔH2 + ΔH3 + ...

ΔHrxn° = ΣnΔHf° (products) - ΣnΔHf° (reactants)

ΔHrxn° ≈ ΣnΔHbond°(breaking) - ΣnΔHbond°(making)

ΔSuniv = ΔSsys + ΔSsurr

S  =  k ln Ω

ΔS  =  qrev / T

ΔS  =  n Cp ln(Tf / Ti)

ΔS  =   nR ln(V2/V1)

ΔStrans  =  ΔHtrans / Ttrans

ΔSrxn° = ΣnS° (products) - ΣnS° (reactants)

G   =   H - TS

ΔG = ΔH - TΔS

ΔGrxn° = ΣnΔGf° (products) - ΣnΔGf° (reactants)

ΔH = TeqΔS

What we provide on the exam cover page

We will provide all data for the exam. Specifically, we will provide a table of thermodynamic values, a table of phase change data, and a table of bond energies. We will also provide values for any constants and conversions needed.

Here is what the bond energy tables look like...

Here is what the thermo tables will look like - although different substances will be provided...

We might even add molar heat capacities (CP,m) to this table as well. And by-the-way...    CP,m is the molar heat capacity at constant pressure.

The Bottom Line...

We will provide the data in some form of table. Be prepared to use any such table of data.

And now, once again, for your enjoyment...

Learning Outcomes for Thermodynamics

Students will be able to...

  1. Identify the system, surroundings, and universe in order to distinguish what is changing during a chemical and/or physical process.
  2. Define and recognize state versus process functions.
  3. Describe the concept of the energy units, including calories, kilocalories, and kilojoule.
  4. Distinguish between kinetic energy, potential energy, and electromagnetic energy.
  5. Deļ¬ne the ļ¬rst law of thermodynamics in the context of internal energy, heat, and work.
  6. Recall sign conventions associated with thermodynamic change.
  7. Define conduction and describe the microscopic view of thermal energy transfer due to molecular collisions.
  8. Deļ¬ne heat capacity, speciļ¬c heat capacity, and molar heat capacity.
  9. Calculate the heat and work associated with chemical and/or physical change.
  10. Calculate PĪ”V (expansion) work for both physical and chemical changes.
  11. Define enthalpy, and calculate the enthalpy change for chemical and/or physical changes.
  12. Calculate change in enthalpy for physical change ā€“ both change in temperature and phase change.
  13. Fully interpret the heating curve of a substance.
  14. Draw and fully interpret energy reaction diagrams.
  15. Differentiate between the change in internal energy and enthalpy for a process, and describe how these quantities are measured (coffee cup vs. bomb calorimetry).
  16. Calculate the change in enthalpy (Ī”H) and internal energy (Ī”U) based on calorimetric data.
  17. Write formation reactions for elements and compounds.
  18. Calculate change in enthalpy based on tabulated data (e.g. Hessā€™s law, formation data, bond enthalpy data).
  19. Deļ¬ne entropy (S) and describe the second law of thermodynamics in the context of Ī”S.
  20. Differentiate between the entropy of system, surroundings, and universe.
  21. Recognize how changes in system properties (T, V, phase, mixing, and composition) will affect the entropy of the system.
  22. Calculate change in entropy for the system and surroundings for a physical change.
  23. Describe entropy using a microscopic perspective of energy distribution (Boltzmann/microstates).
  24. Calculate change in entropy for the system and surroundings for a chemical change.
  25. Deļ¬ne the change in free energy.
  26. Calculate change in free energy (Ī”G) for a chemical change from change in enthalpy and change in entropy.
  27. Use the change in free energy to determine the spontaneity of a chemical and/or physical process at a given temperature.
  28. Calculate Ī”G for a chemical change from tabulated thermodynamic data.
  29. Link Ī”G to the second law of thermodynamics and chemical equilibrium.