by iyell4


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State and explain the factors that increase the entropy of a system.
Changes in matter: the increase in moles of matter as compared to the moles of reactant is an increase in entropy (randomness)

Changes in state: solid is most ordered and gases are least ordered.  moving from solid to liquid to gas is an increase in entropy

Mixing substances:  mixing and dissolving both increase entropy        
Predict whether the entropy change for a given reaction is positive or negative.:

1) water freezing
2) the decomposition of water
3) a precipitation reaction
1) negative.  the system is more ordered (state change)
2) positive.  1.5 moles of gases are produced for every 1 mole of water (moles of particles)
3) negative.  the formation of a solid from aqueous components
Use the signs of entropy change and enthalpy change to predict the temperatures at which a reaction would be spontaneous.
1) when a change is exothermic and entropy is increased, the change is spontaneous at all temperatures. 
2) when a change is endothermic and entropy is decreased, the change is nonspontaneous at all temperatures.
3) when a change is exothermic and entropy is decreased, the change is spontaneous at low temperatures. 
4) when a change is endothermic and entropy is decreased, the change is spontaneous at high temperatures. 
What is the sign or value of gibbs free energy change for a spontaneous reaction? nonspontaneous? an equilibrium?
Spontaneous reactions have a negative delta G.
Nonspontaneous reactions have a positive delta G.
At equilibrium, delta G is zero.

Note: delta G is always written in reference to the forward reaction, so the reverse reaction has the opposite delta G sign.
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