15.3 - Catalysis Flashcards
What does the contact process manufacture?
Sulfuric acid
What is the catalyst in the contact process and what state is it in?
Vanadium(V) Oxide
Solid
What are the 2 reactions in the contact process?
V2O5 + SO2 = V2O4 + SO3
V2O4 + 0.5O2 = V2O5
Describe the mechanism of a solid heterogeneous catalyst.
- Adsorption - one or more reactants becomes attached to the surface of the catalyst.
- Bonds of the reactants are weakened.
- Desorption - The product becomes detached from the surface of the catalyst.
What are the 3 main metals used in catalytic converters?
Platinum
Rhodium
Palladium
What is a homogeneous catalyst?
What is a heterogeneous catalyst?
A catalyst in the same phase as the reactants.
A catalyst in a different phase to the reactants.
In the reaction between S2O82- ions and iodide ions, why is the initial rate of reaction slow?
The two negative charges repel each other.
What catalyses the reduction of S2O8^2- ions to SO4^2- ions?
Fe 2+ ions
Why can’t a magnesium catalyse the reduction of S2O8^2- ions to SO4^2- ions?
Mg^2+ cannot form other oxidation states.
The oxidation of ethanedioate ions by potassium manganate goes through different rates, explain why?
Initially the rate is slow as no Mn^2+ ions are formed so the reaction is uncatalysed.
Rate of reaction speeds up as the Mn^2+ ion concentration increases. So catalyses the reactions.
Rate then decreases as reactants are used up.
What type of catalysis is the oxidation of ethanedioate ions by potassium manganate and what is the species of the catalyst?
Autocatalysis
Mn^2+
The heterogeneous catalyst palladium was suggested for use in this reaction.
Explain how impurities in the gaseous reactants could make the catalyst less effective
Impurities can adsorb onto the catalyst surface.
Impurities can prevent bond weakening in reactants.
Impurities are less likely to desorb from the surface of the catalyst.
