VARIABLE OXIDATION STATES

Question 1

What groups can catalysts be divided into? (2)

Answer 1

-Heterogeneous
-Homogeneous

Question 2

What are heterogeneous catalysts?

Answer 2

are present in a reaction in a different phase than the reactants, they are usually present as solids whereas the reactants are gases or liquids

Question 3

how do Heterogenous catalysts act? (1)

Answer 3

the reactants pass over the catalyst surface, which remains in place so the catalyst is not lost and does not need to be seperated from the products.

Question 4

how do industry make catalysts more efficient? (2)

Answer 4

-increase their surface area
-spread the catalyst onto an inert support medium, this increase the surface- to mass ratio

Question 5

How do catalysts become ineffective? (1)

Answer 5

over time the surfaces may be covered with unwanted impurities this is called poisoning

Question 6

what are some examples of heterogeneous catalysts? (2)

Answer 6

-the haber process
-the contact process

Question 7

what are homogenous catalysts? (1)

Answer 7

when the catalyst is in the same phase as the reactant, an intermediate species is formed

Question 8

what is homogenous catalysis by transition metals? (1)

Answer 8

the uncatalyzed reaction takes place between two ions of the same charge, both negative which repel, therefore giving a high activation energy. Both steps of the catalysed reaction involve reaction between pairs of oppositely charged ions this explains the increase in rate.

Question 9

what is autocatalysis? (1)

Answer 9

when a product of one of the reactions becomes a catalyst for that reaction.