2.5.6 catalysts

what is a catalysts

increases rate without being used up

by providing an alternate route with a lower activation energy

what is a heterogenous catalyst

in a different phase from reactants

what is a homogenous catalyst

in the same phase as reactants

where do reactions of heterogenous catalysts occur

at active sites of the surface

what may lead to catalytic action

adsorption of reactants

what does a support medium do to heterogenous catalysts

maximises surface area

minimises costs

name the heterogenous catalysts in the contact process

V₂O₅

overall equation and steps in the Contact process

overall equation: 2SO₂ + O₂ —→ 2SO₃

step 1: SO₂ + V₂O₅ —→ SO₃ + V₂O₄

step 2: 2V₂O₄ + O₂ —→ 2V₂O₅

what is used as a heterogenous catalyst in the Haber process

Fe

how can catalysts become poisoned

by impurities that block active site and has reduced efficiency - cost implication

when catalysts and reactants are in the same phase what happens

the reaction proceeds through an intermediate species

why are transition metals able to act as homogenous catalysts

they have variable oxidation states

able to oxidise and reduce

partially filled d orbital so can easily lose and gain electrons

reaction between iodide and persulfate ions

autocatalytic reaction between ethanedioate and manganate ions