Free Energy and Redox reaction Flashcards
What is Gibbs free energy?
The change in free energy of a chemical reaction
What is Gibbs free energy of reaction at standard conditions?
All reactants and products at 1 molar, pH 7, and 25 degrees Celsius
What does it mean if the Gibbs free energy of reaction is negative?
Energy release and spontaneous (exergonic)
What does it mean if the Gibbs free energy of reaction is positive?
Reaction not spontaneous (endergonic)
When is Gibbs free energy of reaction at standard conditions thermodynamically favoured?
When ΔG° < 0
What does thermodynamically favoured mean?
- Thermodynamic favorability means a reaction is spontaneous, or the reaction does not require energy to occur
- Forward reaction
What is oxidation?
The loss of electrons (e- donor)
What is reduction?
The gain of electrons (e- acceptor)
What is ∆Gd^o?
Electron donor half-reaction standard free energy
What does
ΔG_a^o
signify in electrochemistry?
Represents the standard Gibbs free energy change for an electron acceptor half-reaction, indicating the spontaneity of the reduction process under standard conditions
What is reversed in the half-reaction?
The electron donor
What are examples of redox reactions?
- Combustion of methane gas
- Corrosions of Metal
What is the donor in the corrosion of steel?
Iron acts as an electron donor
What acts as the acceptor in the corrosion of steel?
Oxygen acts as an electron acceptor
Why does corrosion usually occur?
Due to a collection of moisture
Where does corrosion usually occur?
Near a fastener or at a weld joint
What is henry’s law?
If the pressure of a gas over liquid increases, the amount of gas dissolved in the liquid will increase proportionally.
How does corrosion occur in sewer systems?
- Gaseous hydrogen sulfide dissolves in to condensate at the crown of the pipe and is used as an electron source by sulfide oxidizer
- Acid is produced and dissolves concrete
What is an electrochemical reaction?
Any process either caused or accompanied by the passage of an electric current and involving in most cases the transfer of electrons between two substances
