13.1 Atomic Theory of Matter Based on analysis of chemical reactions Brownian motion
-
Upload
stacey-daniels -
Category
Documents
-
view
30 -
download
1
description
Transcript of 13.1 Atomic Theory of Matter Based on analysis of chemical reactions Brownian motion
APHY20104/20/23 1
13.1 Atomic Theory of Matter Based on analysis of chemical reactions
Brownian motion 1827 – first observed in pollen grains 1905 – Einstein explains motion and
calculates the average atomic diameter to be ~10-10 m
APHY20104/20/23 2
13.2 Temperature and Thermometers
Variations result in changes to the size/shape and electrical resistance of materials.
Calibration using water – why?
Problems concerning pressure
Mercury vs. Alcohol
APHY20104/20/23 3
13.4 Thermal Expansion The separation of atoms in a material is
related to its temperature.
ΔL = αLoΔT for solids
ΔV = βVoΔT for solids, liquids, gases
Applications: thermostats, Pyrex glass, bridges, sidewalks, sea levels
APHY20104/20/23 4
13.4 Thermal Expansion
Water contracts when warmed from 0°C to 4°C then expands.
Fish, water pipes, road repair in the northern US
APHY20104/20/23 5
13.6 The Gas Laws and Absolute Temperature The volume of a gas depends on
pressure and temperature. Equation of State and equilibrium
Boyle’s Law: PV = constant (T = constant)
APHY20104/20/23 6
13.6 The Gas Laws and Absolute Temperature Charles’s Law: V/T = constant (P =
constant) Absolute zero and the Kelvin scale
Gay-Lussac’s Law: P/T = constant (V = constant)
Example: a closed container that is heated or cooled.
APHY20104/20/23 7
13.7 The Ideal Gas Law Combining the previous gas laws and
including the amount of gas, we find that
PV α mT → PV = nRT
n is the number of moles of a gas
R is the universal gas constant 8.314 J/(mol K)
APHY20104/20/23 8
13.9 Avogadro’s Number The ideal gas law can also be written in
terms of the number of molecules in the gas.
PV = NkT
N = nNA with NA = 6.02 x 1023 molecules/mol
k is the Boltzmann constant 1.38 x 10-23 J/K
APHY20104/20/23 9
In class: Problems 10, 29 Other problems ↓
3
3
1.00 10 kg
1.00 m
M
V
6 o 3 o o 2 3
0 210 10 C 1.00 m 94 C 4 C 1.89 10 mV V T
33
3 2 3
1.00 10 kg981kg m
1.00 m 1.89 10 m
M
V
11. The density at 4oC is
When the water is warmed, the mass will stay the same, but the volume will increase according to Equation 13-2.
The density at the higher temperature is
APHY20104/20/23 10
5 3 3
22
23
22 6 4 18 3
Earth
223 3
3 18 3
1.01 10 Pa 2.0 10 m 4.9 10 molecules
1.38 10 J K 300 K
Atmospheric volume 4 4 6.38 10 m 1.0 10 m 5.1 10 m
Galileo molecules 4.9 10 molecules9.6 10 molecules m
m 5.8 10 m
PVPV NkT N
kT
R h
3 33
3
# Galileo molecules molecules 2.0 10 m molecules9.6 10 19
breath m 1 breath breath
45. We assume that the last breath Galileo took has been spread uniformly throughout the atmosphere since his death. Multiply that factor times the size of a breath to find the number of Galileo molecules in one of our breaths.