thermodynamics?

Question

Could someone please tell me what each of these cases would mean:
delta G(reaction) > 0
delta G(reaction = 0
delta S(system) + delta S(surroundings) > 0
delta S(system) < delta S(surroundings)

Answer 1

delta G measures free energy of a chemical reaction. If the free energy number is negative, then the reaction is spontaneous (ie: it will happen under current conditions). If the delta G (free energy) is positive then the reaction will not go to completion and won't happen. If the delta G is 0, then it will go to an equilibrium state where you have equal amount of both reactants and products ( ... I think this is right.. anyone else??)

Therefore,

delta G (reaction) > 0 NO REACTION
delta G (recation) = 0 EQUILIBRIUM STATE..

delta S is a measure of entropy or order of a system. High delta S means an move towards more order (which is not the natural tendency in the universe).

delta G = -T*delta S is the free energy equation

delta S(system) + delta S (surroundings) > 0 means that both are positive numbers and delta G will be negative and the reaction will happen.

delta S(system) < delta S (surroundings) I'm not sure if this is enough information to tell you anything about how a reaction would happen (.. anyone?)

Answer 2

if delta G of the reaction is positive, it means it won't happen spontaneously at the temperature you've specified. if the delta G is 0, then that is the equilibrium temperature at which youll have equal parts reactant and product in the system. Delta S of the system and the delta S of the surroundings is just a law of thermodynamics stating the universe gets more disorganized no matter what. if the delta S of the system is less than the delta S of the surroundings, then you have an exothermic reaction.

Answer 3

delta G is the change in Gibbs Free Energy.

delta G = delta H - T times delta S

These are equations that express whether a reaction is spontaneous or not.

Gibbs was a chemistry professor at Yale University.

Answer 4

"G" I don't know, but "S" refers to entropy. The last two lines are statements of the third law -- entropy, overall, increases, and the entropy of a system decreases less than that of the surroundings increases.