Chemical Reactions and Energy Diagrams

Energy Diagram Basics

• Axes:
  • Y-Axis: Represents energy, specifically Gibbs free energy (G).
  • X-Axis: Represents reaction progress.

Spontaneous Chemical Reactions

• Delta G (∆G): Change in Gibbs free energy, negative for spontaneous reactions.
• Energy Levels:
  • Reactants have higher energy than products.
  • Energy decreases as reaction progresses.
• Activation Energy:
  • Represents the energy barrier that needs to be overcome for a reaction.
  • Positive value because energy is needed to overcome the barrier.

Non-Spontaneous Chemical Reactions

• Delta G (∆G): Positive for non-spontaneous reactions.
• Energy Levels:
  • Reactants have lower energy than products.
  • Energy increases as reaction progresses.
• Activation Energy:
  • Still a barrier to be overcome, starting from reactants side.
  • Positive value, as energy must be climbed.

Chemical Reaction Dynamics

• Equilibrium:
  • Forward reaction (reactants to products) is faster in spontaneous reactions.
  • At equilibrium, the rate of forward and reverse reactions are equal.
• Forward and Reverse Reactions:
  • Spontaneous processes tend to have more forward reaction progress.
  • Equilibrium is achieved when rates of forward and backward reactions equalize.

Catalysts in Chemical Reactions

• Definition: Substances that speed up reactions without being consumed.
• Effect on Activation Energy:
  • Lowers the activation energy by providing an alternative pathway.
  • Pathway with catalyst has a lower energy barrier.
• Catalyst Examples: Platinum, Palladium, Gold, Irons, Heavy metals, Enzymes.
• Delta G (∆G):
  • Remains the same, whether reaction is catalyzed or not.
• Importance: Catalysts allow for faster reactions without altering the overall energy change (∆G).

Upcoming Topics

• Catalyst vs. Non-Catalyst Pathways:
  • Future discussion will involve comparing normal and catalyzed pathways using methane combustion as an example.