Rates of Reaction and Catalysis

Rate of Reaction

• Defined as the change in concentration of reactants or products per unit time
• Typically measured in units of mol/L·s
• Can be expressed as an average rate or an instantaneous rate
• Factors affecting rate of reaction:
  • Concentration of reactants
  • Temperature
  • Surface area of reactants
  • Presence of catalysts

Catalysis

• A catalyst is a substance that speeds up a chemical reaction without being consumed or altered
• Catalysts work by lowering the activation energy required for the reaction
• Types of catalysis:
  • Homogeneous catalysis: catalyst is in the same phase as the reactants
  • Heterogeneous catalysis: catalyst is in a different phase from the reactants
• Examples of catalysts:
  • Enzymes in biological systems
  • Metals in industrial processes

Activation Energy

• The minimum energy required for a chemical reaction to occur
• Represented by the symbol Ea
• Can be thought of as the "energy barrier" that must be overcome for a reaction to proceed
• Factors affecting activation energy:
  • Temperature
  • Presence of catalysts
  • Surface area of reactants

Collision Theory

• A model that explains how chemical reactions occur
• Postulates that reactant molecules must collide with sufficient energy and proper orientation to react
• Factors affecting collision frequency:
  • Concentration of reactants
  • Temperature
  • Surface area of reactants
• The collision theory explains the effects of temperature, concentration, and catalysts on reaction rates

Rate-determining Step

• The slowest step in a reaction mechanism that determines the overall rate of the reaction
• Identifying the rate-determining step is crucial in understanding the kinetics of a reaction
• The rate-determining step can be affected by:
  • Concentration of reactants
  • Temperature
  • Presence of catalysts
• Understanding the rate-determining step can help optimize reaction conditions to increase reaction rates.

Rate of Reaction

• Defined as the change in concentration of reactants or products per unit time
• Measured in units of mol/L·s
• Can be expressed as an average rate or an instantaneous rate
• Factors affecting rate of reaction include concentration of reactants, temperature, surface area of reactants, and presence of catalysts

Catalysis

• A catalyst is a substance that speeds up a chemical reaction without being consumed or altered
• Catalysts lower the activation energy required for the reaction
• Types of catalysis include homogeneous catalysis and heterogeneous catalysis
• Examples of catalysts include enzymes in biological systems and metals in industrial processes

Activation Energy

• The minimum energy required for a chemical reaction to occur
• Represented by the symbol Ea
• Can be thought of as the energy barrier that must be overcome for a reaction to proceed
• Factors affecting activation energy include temperature, presence of catalysts, and surface area of reactants

Collision Theory

• A model that explains how chemical reactions occur
• Reactant molecules must collide with sufficient energy and proper orientation to react
• Factors affecting collision frequency include concentration of reactants, temperature, and surface area of reactants
• The collision theory explains the effects of temperature, concentration, and catalysts on reaction rates

Rate-determining Step

• The slowest step in a reaction mechanism that determines the overall rate of the reaction
• Identifying the rate-determining step is crucial in understanding the kinetics of a reaction
• Factors affecting the rate-determining step include concentration of reactants, temperature, and presence of catalysts
• Understanding the rate-determining step can help optimize reaction conditions to increase reaction rates