Home > Chemistry, Physics > Classical Mechanics: Lecture 33 Notes

Classical Mechanics: Lecture 33 Notes

Overview

Today is a 52 minute lecture on gases.  This is a great supplement to our chemistry work.  I actually watched this one twice.

Details

In liquids, the molecules are almost touching one another.  In gases, the molecules are far apart.  This is why liquids are incompressible and gases are not.

PV = nRT

R = 8.314 J/K

T is temperature in degrees Kelvin

A mole always has 6.02 x 10^23 atoms/molecules/units.  This is Avogadro’s number.  A mole of any gas is 22.4 liters.

Protons are positive, electrons are negative, neutrons are neutral.  Electrons have practically no mass.  A nucleon is a neutron or a proton.

Atomic mass is the number of protons and neutrons.

Mass of a molecule = Atomic mass x 1.66 x 10^-27 kg

Molecules of gas are hitting a wall with average velocity v…

Momentum transfer for one collision= 2 mv

mv2 is independent of the mass of the molecule.

PV = NkT

N = total number of molecules

k = 1.38 x 10^-23 J/K = R/Na

Phase diagrams show states of matter as a function of temperature and pressure.  Solids on the left, gases on the bottom, liquids in between.

Boiler’s Law = constant = PV

A fire extinguisher has radius 15 cm, height, temperature is 300K.  The weight is 10 lbs is 4500 grams of CO2 is 100 moles.  If this were a gas, the pressure would be 10^8 pascals or 1000 atm.  It’s about 60 atm, 900 lbs/in2.  The liquid and gas exist in equilibrium.

Hydrostatic Equilibrium

dP/dy = -dg

dP/dy = -Pmg/(kT)

Air weights roughly 29 grams/mole

Ph = Pi e^(-h/ho)

Put water into a paint can.  Boil it.  As the water boils, the pressure of water becomes 1 atm.  The air will leave.  Then close the top tightly, and the can will implode

Review

Electronegativity: NOF Cl Kr

Z eff = Z – S

PV = nRT

IGL : point source, random motion, elastic collisions, high temperatures, low pressure

(P + n2/a2) (V – nb) = nRT

Temperature Kelvin = T celsuis + 273

Momentum = mv

KE = K = mv2/2

PE = U = mgh

Noble gases: He, Ne, Ar, Kr, Xe, Kr

Atmospheric Layers: D E F1 F2

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