spontaneous reaction - occurs w/o any outside intervention
- usually exothermic, but can also be endothermic
- ammonium salts dissolving in water is endothermic
- DE = q + w
- q = heat absorbed by system from surroundings
- w = work done on surroundings by system
- reversible process - can be restored to its original state using same path
- results in no net change in system, surroundings
- includes all chemical systems at equilibrium
- irreversible process - can only be restored using a different path
- different q, w values from initial process
- includes all spontaneous reactions
- can be fast or slow
Find the conditions surrounding H2O(l) >> H2O(s)
- temperature decreases for water to turn to ice
- energy leaves water
- DH is negative
- product is more orderly/structured than reactant
- DS is negative
entropy - the amount of disorder in a system
- DS = Sfinal - Sinitial
- positive value >> more disorder
- negative value >> less order
- 2nd law of thermodynamics - entropy increases for all spontaneous reactions
- S = 0 for reversible processes
- 3rd law of thermodynamics - entropy = 0 at absolute zero (0K)
- translational motion - entire molecule moving
- vibrational motion - periodical mov’t to/away
- rotational motion - spinning mov’t
- increase temperature >> more mov’t >> more entropy
- decrease temperature >> less mov’t >> less entropy
- Ssolid < Sliquid < Sgas
- å S = å Sproducts - å Sreactants
Arrange the following changes from least increase in entropy to greatest increase in entropy: 1g of ice warmed by 1°, 1g of ice melted, 1g of water frozen, 1g of water evaporated.
- water to liquid is decrease in entropy
- phase changes increase in entropy more than just increasing temperature
- gas has more entropy than liquid
- 1g of water frozen, 1g of ice warmed by 1°, 1g of ice melted, 1g of water evaporated
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