PChem312 f20 w5

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...return to Chem 312 - home

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Monday, Sept 14, 2020

Announcement: Exam I (Ch 1 and 2), Thursday Sept 24th 2-6 pm

- books allowed
- notes allowed
- computers required (computers in CSB 377 will be available)

Section 2.10

Read/skip

Section 2.11: Heat Capacity

- CV,m - molar heat capacity at constant volume.
- CP,m - molar heat capacity at constant pressure.
heat capacities are usually temperature dependent, so CV,m(T) and CP,m(T); more later in Ch 3.
C dep T graph.png
- See Table 2.5: Molar Heat Capacity, CP,m(T), of Gases (298-800K), page 629.

Wednesday, Sept 16, 2020

Sec 2.11: continued

- Heat capacity plot/physical states (Figure 2.14 - Cl2)
Cvm T plot.png

Relationship between CV,m and CP,m...

CP - CV = nR
CP,m - CV,m = R

Sec 2.12/2.13: FINALLY...Calculating ΔU...and more!

ΔU = q + w <-- 1st law of thermodynamics (mathematical form)

Case 1...
Consider a constant volume process where no expansion work (PV work) can be done...reminder for PV work, w = -PΔV...if constant volume (ΔV=0), then no expansion work...and then ΔU = qV, where we add the subscript "V" on q to indicate constant volume.
ΔU = qV
(we will work a few problems like this soon)
Note: it would be nice if there was an equivalent for constant pressure (the much more common why of doing experiments...
See "derivation" of ΔH (enthalpy - the second thermodynamic state function) (page 50-51).
ΔH = qP

Thursday, Sept 17, 2020

0) Heat Capacity Plot of water (use data from Heating/Cooling worksheet)

- using Excel to reproduce Figure 2.14 but for water...
  • Plot Temp (in K) vs CP,m for the
- solid H2O
- liquid H2O
- gaseous H2O
- then use table 2.5 values for H2O (g) to plot temp dependence
Final plot should look like this -->Screen Shot 2020-09-17 at 1.12.16 PM.png.
- using Igor (Wavemetrics Igor 8.0 download/Igor 8.jpg) (78482; VAPG-PDSX-GZLA-XKKY-MVYA-YNUX-KNS)
  • Reproduce Excel graph above

1) (optional/practice) Can you reproduce Figure 2.13 in text (using Excel or Igor)?

2) Thermal imaging camera - insulated mugs

3) Adiabatic Irreversible Expansion Experiment to determine Heat Capacity (details here)


Did not get to these...

- Cowboy Coffee worksheet (here)
- 2-step worksheet (soon).

Friday, Sept 18, 2020

Reminder: Exam 1 (Ch 1/2) Thurs, Sept 24th. 2-6 pm.

Summary sheet here...as of today (ie. more next week)

Review Thurs lab data from Adiabatic Irreversible Expansion Experiment to determine Heat Capacity (details here)