CHEM 120 Lecture Notes - Lecture 13: Intermolecular Force, Chemical Polarity, Partial Charge
15 Jun 2018
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CHEM 120: CHAPTER 11 LIQUIDS, SOLIDS, PHASE CHANGES:
Phase: physically distinct homogenous part of a system compromised of 1 physical state of matter (wave
functions from 110 → on the macroscopic scale)
- Plasmas: (lightning) electrons are mobile, ionized nuclei at high temperatures, abundant form of
matter
T = 2/3 NA/R(1/2mu2) State is determined by interactions between particles
Entropy: measure of disorder within a system (gases can occupy microstates, move rotationally and
translationally so it has lots of disorder, gases > liquids > solids) increase T increase disorder
Enthalpy: stronger intermolecular forces → larger enthalpy, attractive intermolecular forces cause the
particles to rearrange themselves going from gas – liquid – solid by enthalpy changes, type of IF
determines the magnitude of
Solids: large collection of particles, fixed shapes & volumes, less dense than water
Liquids: less viscosity than solids moderate flow and low compressibility (ice is most dense at 4)
Gas: variable shapes and volumes, high compressibility and high flow
Intermolecular Forces: small charges that are separated, what holds a liquid and solid together,
responsible for the existence of condensed states (relatively weak in comparison to bonding forces)
PE = q1q2/40r
The distance across which the PE is interaction is felt (SLIDE GRAPH)
-PE means you are forming a bond
Non-polar molecules that are close to each other will exhibit dispersion forces which will matter more
relevant the closer they are
- Long distances → Ionic dominates
- Short distances → Dispersion dominates
- You can not go past 1/r12 because they are too close, causing repulsion
Ion-Ion interactions: some of the strongest forces between molecules
- Non-directional; each ion interacts equally strongly with all its neighbours (1/r)
- Calculated as crystal lattice energy, where the ions form extended repeating units
- Oppositely charged ions attract
PE = |ZA|ZB|/r
ZA & ZB → magnitudes of the charges on the atoms (i.e. NA+ → z = 1)
The attachment of H2O to solute particles Is called hydration (due to polar character of H2O)
- Water has a permanent dipole
- Mu is the partial charge
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Document Summary
Chem 120: chapter 11 liquids, solids, phase changes: Phase: physically distinct homogenous part of a system compromised of 1 physical state of matter (wave functions from 110 on the macroscopic scale) Plasmas: (lightning) electrons are mobile, ionized nuclei at high temperatures, abundant form of matter. T = 2/3 na/r(1/2mu2) state is determined by interactions between particles. Entropy: measure of disorder within a system (gases can occupy microstates, move rotationally and translationally so it has lots of disorder, gases > liquids > solids) increase t increase disorder. Enthalpy: stronger intermolecular forces larger enthalpy, attractive intermolecular forces cause the particles to rearrange themselves going from gas liquid solid by enthalpy changes, type of if determines the magnitude of (cid:1872)(cid:1870)(cid:1866)(cid:1871)(cid:1872)(cid:1867)(cid:1866) Liquids: less viscosity than solids moderate flow and low compressibility (ice is most dense at 4 ) Solids: large collection of particles, fixed shapes & volumes, less dense than water. Gas: variable shapes and volumes, high compressibility and high flow.
