Difference between revisions of "PChem312 f20 w2"

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''Example of measuring one system variable to get another...''
 
''Example of measuring one system variable to get another...''
:- Pressure data collection: How many moles can you add to a PVC pipe?
+
:- Pressure data collection: [[How_many_moles_PVC_pipe|How many moles can you add to a PVC pipe]]?
 
::* Vernier pressure probe
 
::* Vernier pressure probe
 
::* PVC pipe, cut to length
 
::* PVC pipe, cut to length
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===Friday, Aug 28, 2020===
 
===Friday, Aug 28, 2020===
Read Chapter 2
+
Comments on '''MATH ESSENTIALS 1/2'''
 +
:''new to 4th edition; these use to be in the back of the book.''
 +
 
 +
====Read Chapter 2====
 +
The energy within a system is referred to as the '''internal energy''';internal energy take on two forms:
 +
:1) Kinetic energy
 +
::- translational motion
 +
::- vibrational motion
 +
::- rotational motion
 +
:2) Potential energy
 +
::- Chemical bonds/interactions
 +
 
 +
We discuss gases because they are the easier of all physical states (kind of like a spherical elephant)
 +
 
 +
====Sec 2.1: Internal Energy and !st Law of Thermodynamics====
 +
U <-- internal energy (1st thermodynamic state function)
 +
:U<sub>f</sub> - U<sub>i</sub> = ΔU, the change in the internal energy
 +
::* we cannot measure U<sub>f</sub> or U<sub>i</sub>, only ΔU.
 +
 
 +
'''First Law of Thermodynamics''': the change in the system's internal energy is equal to, but opposite in sign, to the change in the surround's internal energy.
 +
:ΔU<sub>sys</sub> = - ΔU<sub>surr</sub>
 +
 
 +
How does one measure ΔU?
 +
:- changes in the system variables (ΔP, ΔV, ΔT, Δn) are an indication of ΔU; changes in system variables result in either heat (q) transfer or work (w) being done on or by the system; calculation of q or w leads directly to ΔU.
 +
 
 +
::ΔP, ΔV, ΔT, Δn --> q (heat), w (work) --> ΔU
 +
 
 +
:::'''''Heat and work are both defined as a transfer of energy between the system and surroundings.'''''
 +
 
 +
'''''The first Law of thermodynamics can also be stated as:'''''
 +
::'''''ΔU = q + w'''''

Latest revision as of 11:49, 2 September 2020

...return to Chem 312 - home

Join Zoom Lecture Meeting
Join ZOOM Lab Meeting

Monday, Aug 24, 2020

Start reading chapter 1

Questions about Heating Cooling curve Excel?

Sec 1.2: Basic Definitions

- Systems and Surroundings
DEMO: box of system types
  • open/closed...exchange of matter or not
  • adiabatic/diathermal...heat loss or not
  • walls...rigid or moveable/permeable/impermeable
  • system variables...for a gas, pressure (P), temperature (T), volume (V), amount (n)
  • equation of state...for a gas, ideal gas law

We mainly study gases while developing the basic aspects of thermodynamics

  • 0th Law of Thermodynamics: thermometers work!
- Internal Combustion Engine Example Calculation (worksheet)

Sec 1.3: Thermometry (covered in lab)

Wednesday, Aug 26, 2020

Announcements:

- I will verify your Heating/Cooling Curve EXCEL worksheet in lab (were you proactive or are you now reactive?)
- I will verify your combustion worksheet in lab

Questions about Combustion worksheet?

Sec 1.4: Equations of State/Ideal Gas Law

- There is a STATE --> described by STATE VARIABLES --> the relationship between the state variables is the EQUATION OF STATE (variables).
- Equations of state allow us to have predictive powers.
- Why do we fit data to math equations...data reduction...x/y data set of 100 points can be reduced to slope and y-intercept.
- PV=nRT or PV=NkT
  • Dimensional Analysis - nR = Nk ? [R = 0.08314(bar*L)/(mol*K), k = 1.38e-23 J/K, N = number of molecules; 1L = 1 md3, J = Pa*m3, 1 bar = 1e5 Pa) ...yes nR=Nk
- Intensive (density)/Extensive (mass/volume) properties

Side conversation: Do you have an equation of state that we can use to predict your behavior? Myers-Briggs Type Indicator

Sec 1.5: Brief Intro to a Real Gas

- Kinetic Molecular Theory of Gases (handout)
- van der Waals equation; and example --> make this graph in Excel.
Van der Waals eq.PNG
Van der Waals table.PNG

Thursday, Aug 27, 2020

Meet in CSB 378

Activities

- Myers-Briggs discussion
- ACS Talented 12, 2020.
- Sec 1.3: Thermometry
  • Thermometry Types
  • Absolute zero data collection/graphing

Example of measuring one system variable to get another...

- Pressure data collection: How many moles can you add to a PVC pipe?
  • Vernier pressure probe
  • PVC pipe, cut to length
  • PChem tool box

Friday, Aug 28, 2020

Comments on MATH ESSENTIALS 1/2

new to 4th edition; these use to be in the back of the book.

Read Chapter 2

The energy within a system is referred to as the internal energy;internal energy take on two forms:

1) Kinetic energy
- translational motion
- vibrational motion
- rotational motion
2) Potential energy
- Chemical bonds/interactions

We discuss gases because they are the easier of all physical states (kind of like a spherical elephant)

Sec 2.1: Internal Energy and !st Law of Thermodynamics

U <-- internal energy (1st thermodynamic state function)

Uf - Ui = ΔU, the change in the internal energy
  • we cannot measure Uf or Ui, only ΔU.

First Law of Thermodynamics: the change in the system's internal energy is equal to, but opposite in sign, to the change in the surround's internal energy.

ΔUsys = - ΔUsurr

How does one measure ΔU?

- changes in the system variables (ΔP, ΔV, ΔT, Δn) are an indication of ΔU; changes in system variables result in either heat (q) transfer or work (w) being done on or by the system; calculation of q or w leads directly to ΔU.
ΔP, ΔV, ΔT, Δn --> q (heat), w (work) --> ΔU
Heat and work are both defined as a transfer of energy between the system and surroundings.

The first Law of thermodynamics can also be stated as:

ΔU = q + w