T11- ENERGY, THERMODYNAMICS Flashcards
first law thermodynamics
energy cannot be created nor destroyed and can only be converted from one form to the other
entropy
a measure of the systems thermal energy per unit temperature that is unavailable
the more disorder in a system means more entropy
negative entropy
Negative entropy means that something is becoming less disordered - non spontaneous
positive entropy
something is becoming more disordered - these are spontaneous processes and energetically favourable
second law thermodynamics
entropy only increases - in the universe, it is a closed system
- as the universe expands, energy diffuses across and is more spread out, so entropy increases with disorder increasing - this is an irreversible process
metabolism
the total chemical reactions of an organsism
catabolic pathways
process that release energy by breaking down complex molecules to simpler ones
- drive the anabolic reactions
anabolic pathways
consume energy to build complicated molecules from simpler ones
- condensation reactions
in an isolated system
it is unable to exchange energy with surroundings unlike an open system
different forms of energy
kinetic, thermal, potential, light, chemical
all transfer energy from one state to the other
gibbs free energy
^G = ^H -T^S
^G = gibbs free energy
^H = enthalpy change
^S= entropy change
T = temp in klevin
predict if a reaction is feasible or not using gibbs free energy
if ^G <0 = it is feasible
^G> = 0 = not feasible
^G is calculated by
free energy in final state - free energy in initial state
to have a -ve ^G
need to lose energy from initial to final state,
- if the free energy decreases, the system is less likely to change so is more stable
^G measure
a measure of instability and tendemcy to change to a more stable state
- high(+ve)^G are unstable systems and tend to change to a low (-ve) ^G as more stable
example
- a diver on top of a platform has high ^G so is less stable than when in the water
