Write the elementary rate expressions for the following reactions:

A+B<=>C+D (overall 2^nd order rate law; reversible)

A<=>B+C(heterogeneous surface reaction, reversible, with A and B adsorbed on catalyst surface)

A+2 BC+D (reaction first order with respect to A and overall 2^nd order rate law)

A+BC+D (with excess B in the feed)

A+BC+D (The unit of the specific reaction rate is k=(molbar2.h.kg-cat)