Transition Metals 15.3

Question 1

What is a heterogeneous catalyst?

Answer 1

A catalyst that is in a different phase from that of the reactants.

Question 2

What are the 3 steps of the surface adsorption theory?

Answer 2

Adsorption, reaction, desorption.

Question 3

What is part 1 of the reaction step of the Contact process?

Answer 3

The sulphur dioxide adsorbs onto the vanadium(V) oxide and a redox reaction occurs: V2O5 + SO2 –> V2O4 + SO3. The oxidation no. of vanadium decrease from +5 to +4, and the sulphur trioxide desorbs also.

Question 4

What is part 2 of the reaction step of the Contact process?

Answer 4

Oxygen reacts with the V2O4 on the surface of the catalyst and another redox reaction occurs: V2O4 + 1/2O2 –> V2O5. The original catalyst is regenerated because the oxidation number increases from +4 to +5.

Question 5

What is the key reaction in the Contact process?

Answer 5

2SO2 + O2 –> 2SO3

Question 6

What is the main problem with nitrogen monoxide?

Answer 6

It is easily oxidised to form nitrogen dioxide, which can contribute to the formation of acid rain.

Question 7

What is the overall reaction of a catalytic convertor?

Answer 7

2CO + 2NO –> 2CO2 + N2

Question 8

What are the main transition metals used as catalysts in catalytic convertors?

Answer 8

Platinum, rhodium, palladium.