IMT Chapter 1 Probability, Distributions, and Equilibrium

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IMT Chapter 1 Probability, Distributions, and
Equilibrium

• Equilibrium
• Probability
• Distributions
• Equilibrium (Reprise)

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I. Equilibrium

• Three example reactions
• CO(g) Cl2(g) ? COCl2(g)
• N2(g) O2(g) ? 2 NO(g)
• H2(g) I2(g) ? 2 HI(g)
• Chemical reactions tend to run downhill
• What is special about the equilibrium state?
• Keys
• The equilibrium state corresponds to the most
  probable state.
• It (and K) can be predicted on probability alone.
• This works because of the large number of
  particles involved.

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II. Probability

• Probability (P) How likely an event is to occur
• What is the probability of
• Drawing an ace of clubs from a deck of cards?
• Drawing a club?
• Drawing a face card?
• NOT drawing a 10?

• What is the probability of
• Drawing a heart, then a diamond?
• Drawing two diamonds in a row?
• Rolling five die and getting all 6s? (YAHTZEE!)
• Rolling five die and getting all the same number?
• NOT drawing a 10 from a deck of cards?

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III. Distributions

• Consider a four card set club, spade, diamond,
  heart
• How many ways can these be distributed into two
  sets (hands) of two?
• In how many cases are both cards in a hand the
  same color?
• In how many cases are the cards in a hand
  different colors?
• Most probable distribution is 2 RB
• How probable is the most probable distribution?

• Switch to chemistry Black and red cards H and
  D atoms
• Hydrogen isotope exchange reaction H2 D2 ? 2
  HD
• Whats the most probable state?
• How probable is the most probable state?

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IV. Equilibrium (Reprise)

• So
• If the equilibrium state is the most probable,
  and
• fluctuations from the most probable state are
  indiscernible
• then probability can be used to predict
  equilibrium constants