Catalysis Flashcards
What does a catalyst do?
Speed up the rate of reaction by providing an alternate route for the reaction to occur
By lowering the activation energy
Why are transition metals good catalysts?
They have variable oxidation states
What is a heterogeneous catalyst?
Different state
Where catalyst is in different state to reactants
What is a homogenous catalyst?
In the same state a reactants
How are heterogeneous catalysts used?
They’re attached to a mesh to create a large surface area
What is the contact process?
The process that makes sulphuric acid
Overall reaction:
So2(g) + 1/202 (g) to SO3(g)
Vanadium 5 V205(s) is the catalyst for the first step of the reaction
S02+ V205 to S03 + V204
Catalyst is reformed:
V204 + 1/202 to V205
This is heterogeneous
What is the haber process?
N2 + 3H2 reversible 2NH3
Uses iron catalyst
This is heterogeneous
What is a catalytic converter?
Rhodium and platinum on a mesh to remove noxious fumes
2C0 + 2N0 to 2C02 + N2
This is heterogeneous
What is catalytic poisoning?
Leaded petrol poisons catalyst
Lead sticks to surface of catalyst so catalytic conversion can’t take place
Can be undone by cleaning the catalytic converter but it costs money
What is the reaction between iodine and peroxodo Disulphate ions?
A slow reaction due to repulsion between both ions
Catalyst of iron 2+
All are in solution
S208 2- + Fe2+ to S04 2- + Fe3+
2Fe3+ +2I- to Fe2+ +I2
To make sulphate ions
Homogeneous catalysis
What is the reaction of manganite and ethane dioate ion?
Homogeneous catalysis
Autocatalysis
First step is slow bc of repulsion but produces catalyst:
2Mn04^- +16H+ 5C2O4 2- to 2Mn2+ +8H20 + 10C02
Second step is fast as is third step till reactants run out:
4Mn2+ +Mn04- +8H+ to 5Mn3+ +4H20
Mn3+ C204 2- to Mn2+ + 2C02
Manganese 2+ ion is the catalyst
Why don’t s block elements act as catalysts?
They don’t have variable oxidation states
Why is activation energy high when there’s no catalyst?
Bc there’s repulsion between the two negative ions
Why is the activation energy low when reacting iodine and peroxodo dishulphate ions?
Bc there is attraction between catalyst and reactants
