Rate equation

The oxidation of SO₂, with a Pt catalyst is a two step sequence of elementary reactions: 

1) O₂ + 2X ⇔ 2{O-X} 

2) SO₂ + {O-X} → SO₃ + X

In which X is a site of the catalyst. Assume that the rate limiting step is sub-reaction 2. 

A. Does the concentration of product influence on overall reaction rate? 

B. Derive a rate equation for the rate of formation of SO₃ with only constants and any necessary concentrations of O₂, O₂, SO₃ and total amount of sites. 

C. How fast is the formation of SO₃ compared to the consumption of SO₂ and O₂, respectively? 

Er helt på bare bund i forhold til at løse opgaven... Nogen som kan hjælpe? 

a) The overall reaction rate is not affected by the concentration of products. 

b) ? 

c) ?