chemistry midterm 1

Entropy (s)

disorder

enthalpy (H)

heat of rxn

Free energy (g)

spontaneity of rxn

1st Law of Thermodynamics

Energy of the Universe is conserved: q=0

2nd Law of Thermodynamics

Entropy of the Universe is increasing

3rd Law of Thermodynamics

the perfect crystal (s=0) is formed at 0 kelvins

Entropy of states

gases Entropy>liquids Entropy>solids Entropy

Entropy and Temperature

entropy of a substance increases as the temperature does.

∆H (enthalpy)

(-) ← exothermic soln (rxn losing energy)

(+) ←endothermic soln (rxn gaining energy)

∆S (entropy)

(-) more order

(+) more disorder

∆G (free gibs)

(-) spontaneous

(+) non-spontaneous

∆SUniverse=

∆S_sys+∆S_surr

addition of salt to water

decreases the temperature

At constant pressure ∆H=?

q

entropy of similar compounds w/ the same state

complex substances entropy > less complex similar substance

Entropies of Ionic solids

these increase as the attractive forces btwn ions decrease. attractive forces btwn ions increase as charge increases and decrease as size increases