Reaction Favorability (Gibbs' Energy)

Gibbs’ Energy

An equation that determines the favorability of an reaction

In ΔG^0’, what does the superscript 0’ mean?

At physiological pH and temperature

List the factors of ΔG

• The degree of enthalpy

• The degree of entropy

Enthalpy

The amount of heat

Entropy

The amount of disorder in a system

To maintain the order in a system, the system must put in…

a constant input of work

What is ΔG?

The amount of energy input required for a reaction to proceed

ΔG is associated with what?

Activation energy (E_A)

What is associated with a positive ΔG?

• Non-spontaneous (reaction will not happen by itself)

• Unfavorable (without an enzyme, this reaction won’t happen)

• Endergonic (putting in energy)

What is associated with a negative ΔG?

• Spontaneous (reaction can happen by itself)

• Favorable

• Exergonic (energy is released)

When a reaction’s ΔG is EXTREMELY negative, how frequently will the said reaction be carried out?

The reaction will always happen

What is the relationship to ΔG and its sign? Finish the statements below! (likely/unlikely/positive/negative)

The closer ΔG is to zero, the more ________ the reaction will happen. The more _______ ΔG is, it is more ________ to happen

likely; positive; unlikely

Terminal electronic acceptor

The last compound to receive an electron

What is aerobic respiration’s terminal electron acceptor?

O₂

What is anaerobic respiration’s terminal electron acceptor?

Inorganic molecule other than O₂

What is fermentation’s terminal electron acceptor?

A portion of the original organic substrate

What is the ΔG of O₂ in aerobic respiration?

-2800 kJ per mol

What is the ΔG of NO₃ in anaerobic respiration?

-2670 kJ per mol

What is the ΔG of SO₄ in anaerobic respiration?

-300 kJ per mol

What is the ΔG of CO₂ in anaerobic respiration?

-340 kJ per mol

What is the ΔG of pyruvate in fermentation?

-25 kJ per mol

Out of the three processes, which process is the most energetically favorable process?

Aerobic respiration