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5 Ex exam 5    12/5

We will continue with our official Exam Procedure page. Check it out and know what to expect on Tuesday.

Coverage for Exam 5: Exam 5 covers all of the Thermodynamics chapter on the gchem site. This will correspond with the material on LE's 23-30 and HW09 and HW10. There are two extra practice assignments (13 and 14) on canvas which are there as exam 5 warm up assignments.

Length / Time for Exam 5: Nothing new here - you should once again expect about 20 multiple choice questions. The questions will have a range of point values from 4 points to 6 points although the default will be 5 points. Remember that the point values are included with all questions. The exam is given during class time (9:30-10:45, 11-12:15) which is 75 minutes total which includes the handout time and pick up time.

It is always a good idea to continue knowing your nomenclature for a chemistry class. However, there are not going to be any direct nomenclature questions.

CALCULATORS will definitely be needed on this exam. All students need to bring their OWN scientific calculator (no graphing calculators).

LOTS of Extra Practice Problems from Old Thermo Exams

First Law: Exam 7 Practice Problems | KEY

Second Law: Exam 8 Practice Problems | KEY

Main Equations/Formulas for Exam 5

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

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)
sad, but no isothermal expansion on the exam - so you can omit these two equations
w   =  –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

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. Define the first 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. Define heat capacity, specific heat capacity, and molar heat capacity.
  9. Calculate the heat and work associated with chemical and/or physical change.
  10. Calculate PΔV (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 – 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 (ΔH) and internal energy (ΔU) based on calorimetric data.
  17. Write formation reactions for elements and compounds.
  18. Calculate change in enthalpy based on tabulated data (e.g. Hess’s law, formation data, bond enthalpy data).
  19. Define entropy (S) and describe the second law of thermodynamics in the context of ΔS.
  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. Define the change in free energy.
  26. Calculate change in free energy (ΔG) 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 ΔG for a chemical change from tabulated thermodynamic data.
  29. Link ΔG to the second law of thermodynamics and chemical equilibrium.