Standard Entropies, So

• Every substance at a given temperature and in a specific phase has a well-defined Entropy

• At 298o the entropy of a substance is called
  So - with UNITS of J.K-1.mol-1
  

• The larger the value of So, the greater the degree of disorder or randomness

e.g. So (in J.K-1mol-1) : Br2 (liq) = 152.2

Br2 (gas) = 245.5

For any process:

?So = ? So(final) - ? So(initial)

?So(vap., Br2) = (245.5-152.2) = 93.3 J.K-1mol-1

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