^^Entropy^^: dispersal of matter/energy in sample of matter
changes of entropy can be seen as how dispersed the matter/energy is
entropy increases when matter is more dispersed
individual particles at increased entropies are more free to move and occupy more space
With gases:
entropy also increases when energy is more dispersed
according to KMT, K.E among particles broadens when temperature increases
entropy increases when temperature increases
entropy change can be calculated from absolute entropies in individual species
most substances have a nonzero value for absolute entropy unlike enthalpy
when calculating, number of moles of each substance have to be considered
^^Find delta S with: ΔS=∑S(products)−∑S(reactants)^^
entropy is positive if : phase changes occur as, solid to liquid to gas or if number of moles increase from reactants to products
entropy is negative if: phase changers occur as, gas to liquid to solid
^^Gibbs free energy:^^ △G describes if a reaction is thermodynamically favorable or unfavorable
^^Thermodynamically favorable:^^ equation proceeds to equilibrium with no outside factors
reminder! just because reaction is favorable does not mean it happens quickly
in Gibbs free energy all reactants and products are in standard states (pure substance, 1.0M, 1 atm)
^^Find delta G with: ΔG=∑G(products)−∑G(reactants)^^
thermodynamically favorable, G=negative
thermodynamically unfavorable, G=positive
G can be calculated from enthalpy and entropy with: ^^ΔG=ΔH-TΔS^^ * t=temperature
^^Find K with: K=e-GT/RT^^
Find Delta G with: ΔG° = -RTlnK *R = 8.314 J mol-1 K-1
^^Coupling:^^ when two reactions share an intermediate, they can be coupled, Hess’s law can be applied and the sum of the reactants’ ΔG values makes overall process favorable when added