Free Energy and Redox reaction

Question 1

What is Gibbs free energy?

Answer 1

The change in free energy of a chemical reaction

Question 2

What is Gibbs free energy of reaction at standard conditions?

Answer 2

All reactants and products at 1 molar, pH 7, and 25 degrees Celsius

Question 3

What does it mean if the Gibbs free energy of reaction is negative?

Answer 3

Energy release and spontaneous (exergonic)

Question 4

What does it mean if the Gibbs free energy of reaction is positive?

Answer 4

Reaction not spontaneous (endergonic)

Question 5

When is Gibbs free energy of reaction at standard conditions thermodynamically favoured?

Answer 5

When ΔG° < 0

Question 6

What does thermodynamically favoured mean?

Answer 6

• Thermodynamic favorability means a reaction is spontaneous, or the reaction does not require energy to occur
• Forward reaction

Question 7

What is oxidation?

Answer 7

The loss of electrons (e- donor)

Question 8

What is reduction?

Answer 8

The gain of electrons (e- acceptor)

Question 9

What is ∆Gd^o?

Answer 9

Electron donor half-reaction standard free energy

Question 10

What does
ΔG_a^o
signify in electrochemistry?

Answer 10

Represents the standard Gibbs free energy change for an electron acceptor half-reaction, indicating the spontaneity of the reduction process under standard conditions

Question 11

What is reversed in the half-reaction?

Answer 11

The electron donor

Question 12

What are examples of redox reactions?

Answer 12

• Combustion of methane gas
• Corrosions of Metal

Question 13

What is the donor in the corrosion of steel?

Answer 13

Iron acts as an electron donor

Question 14

What acts as the acceptor in the corrosion of steel?

Answer 14

Oxygen acts as an electron acceptor

Question 15

Why does corrosion usually occur?

Answer 15

Due to a collection of moisture

Question 16

Where does corrosion usually occur?

Answer 16

Near a fastener or at a weld joint

Question 17

What is henry’s law?

Answer 17

If the pressure of a gas over liquid increases, the amount of gas dissolved in the liquid will increase proportionally.

Question 18

How does corrosion occur in sewer systems?

Answer 18

• 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

Question 19

What is an electrochemical reaction?

Answer 19

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