9.3.1 Types of Catalysts

• What is a catalyst?

  Speeds up reaction
• Homogeneous catalysts exist in the same physical phase as the reactants.
• Heterogeneous catalysts exist in a different phase than the reactants.
• In what phase do homogeneous catalysts typically exist?

  Liquid or gaseous
• In what phase do heterogeneous catalysts typically exist?

  Solid
• Match the type of catalyst with an example reaction:

  Homogeneous ↔️ Ester hydrolysis

  Heterogeneous ↔️ Hydrogenation of alkenes
• Why are homogeneous catalysts difficult to separate from products?

  Same physical phase
• Heterogeneous catalysts are less effective than homogeneous catalysts but reusable.
• By lowering the activation energy, a catalyst allows more reactant molecules to overcome the energy barrier
• What type of catalyst forms an intermediate complex in solution?

  Homogeneous
• In heterogeneous catalysis, reactants adsorb onto the catalyst surface.
• Why are heterogeneous catalysts easily separated from products?

  Different physical phase
• In acid-catalyzed ester hydrolysis, HCl acts as a homogeneous catalyst.
• What is an example of a heterogeneous catalyst used in the hydrogenation of ethene?

  Platinum
• Heterogeneous catalysts are less effective per unit mass than homogeneous catalysts.
• What is the role of a catalyst in a chemical reaction?

  Lowers activation energy
• In the hydrogenation of ethene, platinum acts as a heterogeneous catalyst.
• Homogeneous catalysts exist in the same phase as the reactants.
• Match the type of catalyst with an example reaction:

  Homogeneous ↔️ Acid-catalyzed ester hydrolysis

  Heterogeneous ↔️ Platinum-catalyzed hydrogenation
• Why are heterogeneous catalysts easily separated from reaction products?

  Different physical phase
• Homogeneous catalysts are highly effective but difficult to separate.
• Homogeneous catalysts are difficult to separate from products, while heterogeneous catalysts are easily separated.
• Which type of catalyst is highly effective but less reusable?

  Homogeneous
• Homogeneous catalysts exist in the same phase as the reactants.
• Match the catalyst type with its phase:

  Homogeneous ↔️ Same phase as reactants

  Heterogeneous ↔️ Different phase than reactants
• Steps in the mechanism of homogeneous catalysis

  1️⃣ Coordination

  2️⃣ Activation

  3️⃣ Product Formation

  4️⃣ Regeneration
• An example of homogeneous catalysis is acid-catalyzed ester hydrolysis.
• Why are homogeneous catalysts difficult to separate from products?

  They are in the same phase
• Homogeneous catalysts are highly effective but less reusable.
• Homogeneous catalysts exist in the same phase as the reactants.
• In what state do homogeneous catalysts typically exist?

  Liquid or gaseous
• Homogeneous catalysts form intermediate complexes with reactants in solution.
• Heterogeneous catalysts exist in a different phase than the reactants.
• In what state are heterogeneous catalysts typically found?

  Solid
• In heterogeneous catalysis, reactants adsorb onto the catalyst surface.
• Heterogeneous catalysts are easily separated from products.
• Why are heterogeneous catalysts less effective per unit mass?

  They are reusable
• Homogeneous catalysts lower the activation energy of a reaction.
• Steps in the mechanism of homogeneous catalysis

  1️⃣ Coordination

  2️⃣ Activation

  3️⃣ Product Formation

  4️⃣ Regeneration
• What happens during the coordination step of homogeneous catalysis?

  Catalyst binds to reactants