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 | ||
| Line 67: | Line 67: | ||
===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
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.
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