Difference between revisions of "PChem312 f20 w5"

Latest revision as of 16:31, 31 March 2021

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

- C_V,m - molar heat capacity at constant volume.

- C_P,m - molar heat capacity at constant pressure.

heat capacities are usually temperature dependent, so C_V,m(T) and C_P,m(T); more later in Ch 3.

- 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)

Relationship between C_V,m and C_P,m...

C_P - C_V = nR

C_P,m - C_V,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 = q_V, where we add the subscript "V" on q to indicate constant volume.

ΔU = q_V

(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 = q_P

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 C_P,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 -->

.

- using Igor (Wavemetrics Igor 8.0 download/

) (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)

@@ Line 15: / Line 15: @@
 :- C<sub>V,m</sub> - molar heat capacity at constant volume.
 :- C<sub>P,m</sub> - molar heat capacity at constant pressure.
-::heat capacities are usually temperature dependent, so C<sub>V,m</sub> (T) and C<sub>P,m</sub> (T); more later in Ch 3.
+::heat capacities are usually temperature dependent, so C<sub>V,m</sub>(T) and C<sub>P,m</sub>(T); more later in Ch 3.
 :[[File:C_dep_T_graph.png|400px]]
-:- Heat capacity plot/physical states
+:- 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 - Cl<sub>2</sub>)
 :[[File:Cvm_T_plot.png|400px]]
-===Wednesday, Sept 16, 2020===
+Relationship between C<sub>V,m</sub> and C<sub>P,m</sub>...
+:::C<sub>P</sub> - C<sub>V</sub> = nR
+:::C<sub>P,m</sub> - C<sub>V,m</sub> = 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 = q<sub>V</sub>, where we add the subscript "V" on q to indicate constant volume.
+::::'''ΔU = q<sub>V</sub>'''
+::::''(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 = q<sub>P</sub>'''
 ===Thursday, Sept 17, 2020===
+) Heat Capacity Plot of water (use data from [[Media:Heating_cooling_curve.doc|Heating/Cooling worksheet]])
+:- using Excel to reproduce Figure 2.14 but for water...
+::* Plot Temp (in K) vs C<sub>P,m</sub> for the
+::::- solid H<sub>2</sub>O
+::::- liquid H<sub>2</sub>O
+::::- gaseous H<sub>2</sub>O
+::::- then use table 2.5 values for H<sub>2</sub>O (g) to plot temp dependence
+:Final plot should look like this -->[[File:Screen Shot 2020-09-17 at 1.12.16 PM.png|100px]].
+:- using Igor ([https://www.wavemetrics.com/downloads/current/Igor%20Pro%208 Wavemetrics Igor 8.0 download]/[[File:Igor_8.jpg|50px]]) (78482; VAPG-PDSX-GZLA-XKKY-MVYA-YNUX-KNS)
+:::*Reproduce Excel graph above
+) ''(optional/practice)'' Can you reproduce Figure 2.13 in text (using Excel or Igor)?
+) Thermal imaging camera - insulated mugs
+) '''''Adiabatic Irreversible Expansion''''' Experiment to determine Heat Capacity (details [[AIE_exp|here]])
+Did not get to these...
+: - Cowboy Coffee worksheet ([[Media:cowboy coffee.pdf|here]])
+: - 2-step worksheet (soon).
 ===Friday, Sept 18, 2020===
+Reminder: Exam 1 (Ch 1/2) Thurs, Sept 24th. 2-6 pm.
+:Summary sheet [[Media:Exam_1_review.pdf|here]]...as of today (ie. more next week)
+Review Thurs lab data from '''''Adiabatic Irreversible Expansion''''' Experiment to determine Heat Capacity (details [[AIE_exp|here]])