PChem312 f20 w2

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

0^th 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)

U_f - U_i = ΔU, the change in the internal energy

we cannot measure U_f or U_i, 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_sys = - ΔU_surr

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