Total energy =
usable energy + unusable energy
H=
total potential energy
in a compound; based on enthalpy
enthalpy
energy found in bonds of molecule
∆H–negative v positive
If ∆H, or the change in H during a reaction is negative, that means that energy is being released. This is spontaneous.
We want to have a –∆H because that means that with regard to the
total energy of the system, energy has been released.
Equation + explanation
∆G = ∆H – (T∆S)
Free (available) energy = change in total energy – (temperature x
Change in disorder)
T
temperature in K
S=
unusable energy
Entropy-
disorder
S–negative v positive
If ∆S is positive, then randomness has increased, which is spontaneous
We want ∆S
to be positive because that means randomness is increased, which
is more spontaneous. The – sign in front of the S will make the ∆G
also more negative
G=
usable/ available energy, or Gibbs free energy
free energy
Free energy- portion of a system’s energy that can perform work
G–positive vs negative
If free energy is released by a reaction, (meaning that the free
energy at the end of the reaction is less than the free energy at the
start of the reaction), ∆G will be negative. This means that the
reaction is spontaneous.
Energy coupling
using the energy from the exergonic reactions to
power the endergonic ones
Cells usually use ATP as a coupling agent. By breaking down
ATP and releasing energy, that energy can be used to
power an endergonic reaction
a -7.3 could power a +5.4
