CHM110H5 Study Guide - Midterm Guide: Chemical Polarity, Molar Mass, Phenolphthalein

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26 Nov 2012
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Study Notes for Chemistry Midterm 2 - Friday, Nov 9th
Kinetic Molecular Theory
molecules are far apart; most of the volume is empty space
molecules are in constant motion; they travel in straight line paths
molecules exert no force on each other excepting during collisions
the average kinetic energy of the molecules depends on the temperature
o (1) at constant volume V
o as T ↑, velocity ↑
o as velocity ↑, there are more collisions between molecules and container so P↑
o therefore, P α T at constant V
o (2) if V is variable
o at T ↑, velocity ↑ and P ↑
o but as P ↑ the container expands until P↓ back to original P
o therefore, P α 1/V at constant T, and v α T at constant P
o (3) absolute T
o since v α T, as T↓, v↓
o when v = 0, ½mv2 = 0
o a temperature below this point would have no physical meaning (absolute zero)
Diffusion and Effusion
Diffusion → process by which a gas mixed with another; random movement of gas
particles in a medium
Effusion → process by which a gas escapes a container through a small opening; gas
movement through a hole
Molecular Velocities
o at constant T, the average kinetic energy and velocity are constant
o there is a wide range of values for the kinetic energy and velocity of individual
molecules
o relative average velocities depend on relative masses
Graham's Law:
½m1v12 = ½m2v22 at constant T
v1 = √m2
v2 m1
So, the heavier the molecule, the slower it moves.
Diffusion and effusion rates are known as r, so:
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r1 = M2
r2 M1
Mean Free Path: the average distance a particle travels before it collides with other particles
effusion < diffusion < molecular velocities (due to collisions)
Van Der Waal's Equation:
(P + n2a/V2)(V-nb) = nRT
where,
P = pressure
n = moles
a = constant, measure of strength of the intermolecular forces between molecules
V = volume
n2/V2 = concentration2
b = excluded volume/mol
(P + n2a/V2) is an adjustment to the Pressure of the container, because the attraction between
the molecules is not negligible, especially if the container is so small
(V-nb) is also another adjustment but to the Volume of the container, because molecules take
up space, and if the container is small, the space the molecules occupy will not be negligible
*The lower the Van Der Waal's constants, the lower (colder) the boiling point
ρ = MP/RT (molar mass x pressure/r x temperature)
Compressibility Coefficient:
z = PV/RT
z should be equal to 1 if gases behave ideally
the extent to which z deviates from 1 is a measure of how non-ideal the behaviour is
for every gas, at some temperature it will behave ideally
this is called the Boyle Temperature
based on chemical composition and Van Der Waal's numbers
Coulomb's Law
F α q1q2/r2 F = kq1q2/r2 F = q1q2/4πϵor2
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Document Summary

Study notes for chemistry midterm 2 - friday, nov 9th. Molecules are far apart; most of the volume is empty space. Molecules are in constant motion; they travel in straight line paths. Diffusion process by which a gas mixed with another; random movement of gas particles in a medium. Effusion process by which a gas escapes a container through a small opening; gas movement through a hole. Molecular velocities: at constant t, the average kinetic energy and velocity are constant, there is a wide range of values for the kinetic energy and velocity of individual molecules, relative average velocities depend on relative masses. So, the heavier the molecule, the slower it moves. Diffusion and effusion rates are known as r, so: r1 = m2 r2 m1. Mean free path: the average distance a particle travels before it collides with other particles effusion < diffusion < molecular velocities (due to collisions) Van der waal"s equation: (p + n2a/v2)(v-nb) = nrt where,

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