Chapter 4B - Catalysts
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What is a catalyst?
Any substance that causes a reaction to proceed faster/slower without being consumed itself. Provides alternative reaction pathway that has a lower activation energy
How does a Catalyst work?
• Binds with reactant particles, weakening the bonds within the reactants • decreases the amount of energy required to break bonds • greater proportion of collisions have energies > EA
add percentage yield What is the effect of a catalyst?
• lowers the EA for both the forwards & reverse reaction by the same amount • The percentage yield remains unchanged • Does not affect the enthalpy change
What are some common forms of catalysts?
Generally solid form * porous (gauze) * powdered (increase SA) * pure or compounds of transition metals
What is an advantage of using a catalyst?
Can be used in a variety of reactions, unlike enzymes which are specific
What are the types of catalysts?
• Heterogenous • Homogenous
Define Homogenous
Catalyst is in the same physical state as the reactants and products
Define Heterogenous
Catalyst is in a different physical state compared to the reactants and products (most common)
Why do we use solid catalysts in guaze/powdered forms?
• rely on reactant molecules absorbing onto the catalyst surface • forms maximise the surface area • improves catalyst efficiency