catalysts Flashcards
why is a tm a good catalyst
because they can change their oxidation states by losing or gaining electrons within their d-orbitals
what is a heterogeneous catalyst
where the catalyst is a different physical state to the reactants
what is a homogeneous catalyst
where the catalyst is the same physical state as the reactants
what is an example of a heterogeneous catalyst
Fe(s) in the haber process
N2(g) +3H2(g)——-> 2NH3(g)
iron is solid N2 and hydrogen are GAS
how does a homogeneous catalyst work
- by forming an intermediate species
the reactants combine with the catalyst to form the intermediate - this will react to form products and reform the catalyst
how does a catalyst actually lower ea
the Ea needed to form the intermediates to then form the products is lower than the Ea needed to just go straight from reactant to product
where a heterogeneous catalyst put into practise
on the surface of the catalyst
- therefore this is why increasing SA for this type of catalyst is good more molecules can react at the same time - so faster rate of reaction.
how does a catalytic converter work
a ceramic lattice is coated with a thin layer of rhodium( aka catalyst)
2CO (g) +2NO(g) ——–> 2CO2(g) + N2(g)
the lattice structure increases the surface area and allows for a faster rate of reaction
define autocatalysis
where the product of the reaction acts as a catalyst
what is an example of an autocatalyst
Mn2+
which element will poison a catalytuc converter
lead - you must have unleaded petrol to prevent this
what is catalyst poisoning
where reactants are blocked from adsorbing to the catalysts’ surface
which element poisons Fe catalysts in the haber process
sulphur
