Thermodynamics Flashcards
Draw the reduction energy level diagram
Reduction occurs when the energy of the electrode increases above the lowest vacant molecular orbital of the compound
Draw the oxidation energy level diagram
Oxidation occurs when the energy of the electrode dips below the highest occupied molecular orbital of the compound
Write the Change in Gibbs Energy equation and denote the symbols
Write the Change in Gibbs Energy equation from the differential form
What is the equilibrium potential directly related to?
Free energy change
What are the conditions of standard lectrode potentials?
- At equilibrium.
- Potential associated with a reduction reaction when at 1M, 1 atm, and at 25 °C
- Measured with respect to standard hydrogen electrode (SHE)
It is the quantitative measure for the thermodynamic tendency of a redox couple to undergo reduction or oxidation
What is a oxidizing agent (oxidant)?
Molecule that gains electrons
What is a reducing agent (reductant)?
Molecule that loses electrons
What is the equation for equilibrium potential of a cell?
What would the values of ΔG and Ecell be so that the reaction is feasible (proceeds spontaneously)?
Ecell must be positive
So ΔG must be negative
Comparing two Ecell values - which one would get oxidised (loses electrons)?
Ecell value with lower standard reduction potential
Higher value gets reduced
What is the Nernst equation and what does it account for?
Nerst equation shows the potential of the electrochemical cell depends on the composition
What is the thermodynamic reaction quotient equation?
What do thermodynamics / Nerst equation not consider?
- Transition states, mass transfer, energy barriers (kinetic effects)
- Internal resistance: solutions are not perfect conductors
When will thermodynamics / Nerst model work?
Before the current flows (open cicuit)
Nerst model is based of thermodynamics (NOT kinetics!) - static modelrather than dynamic rate model
Problem occurs when we use current