17.4- WHY DO CHEMICAL REACTIONS TAKE PLACE? Flashcards
What do chemists use the term feasible or spontaneous to describe?
reactions which could happen on their own accord
What do the terms feasible/spontaneous not take account of?
rate of reaction
What do many processes that happen spontaneously involve?
mixing or spreading out
When may endothermic reactions be spontaneous?
if they involve spreading out, randomising or disordering
What is entropy?
randomness of a system
What would the entropy change ΔS be like if the products are more disordered than the reactants?
positive value for entropy change ΔS
In general, what is the order of entropy values for the three states of matter?
gases > liquids > solids
What are the two factors that govern the feasibility of a chemical reaction?
enthalpy change
entropy change
For a reaction to be feasible, what must the change in Gibbs free energy ΔG be like?
negative
What is the equations for the change in Gibbs free energy?
ΔG = ΔH - TΔS
As ΔG depends on temp. because of the term TΔS, what does this mean?
some reactions may be feasible at one temp and not at another
What does ΔG = 0 represent?
point at which reaction just feasible
