Electron Transfer Reactions Flashcards
(24 cards)
A catalyst makes the ΔG _
Lower
What can the difference between ΔGs tell us?
How good the enzyme is
The enhancement
What causes the enhancement?
Differences in the transmission coefficient and the difference between the Gibbs free energy of the transition state.
What are typical enhancements for enzyme catalysed reactions?
10^12 - 10^15
What is an inner sphere reaction?
One that involves the making and breaking of bonds
What is an outer sphere reaction?
One that does not involve the making and breaking of bonds, for example electron transfer reactions.
The donor orbital is _ in energy than the acceptor orbital
Higher
What does Marcus Theory introduce?
The concept of the reorganisation energy
What is the reorganisation energy?
λ
The cost of moving from the equilibrium state to a non-equilibrium state
How to find λ on a diagram
The distance directly up from the minimum of the first well to where it hits the second well
Reorganisation energy remains _ for a system
Constant
As the product becomes more favourable the amount of energy required for the transfer becomes _
Smaller
λ becomes smaller
What is the Marcus inverted region?
Where -ΔG > λ
Reaction becomes so favourable that it slows down.
What can electrons be considered as
Particles and/or waves
What will happen to the wave function as it passes through the barrier?
It will decay exponentially
What does the wave function predict?
How likely it is for something to exist somewhere
The amplitude of the oscillation is representative of what?
The probability
The longer the barrier is the _ the chance of the wave function having amplitude
Smaller
Tunnelling is very dependent on what?
Distance
When does tunnelling occur?
When there is a probability that the particle can exist in the product potential well.
Which species display quantum tunnelling?
- Electrons
- Isotopes of protons
- Isotopes of hydrogen
- Isotopes of hydrides
Higher rates of tunnelling for _ isotopes
Lighter
What is the most important factor in tunnelling?
Shape of the barrier
Width especially
Can electrons move across a whole protein?
Yes
