When we add reactions
we have to take the product of those two K values
so if I take A plus B yields C
I can write my law of mass actions so my K 1 value there
when I look at B plus D yields E
I can write K 2 so E over B and D when I look at B plus D yields E
I can write K 2 so E over B and D
now if I add those two reactions I end up with A
plus 2 B plus D as my reactants side
and I end up with C and E
on my product side
so now if I write the K 3
if I write the equilibrium expression for that overall reaction
I get C times E over A B squared D
if I look at K 1 and K 2
I see this is simply the product if I look at K 1 and K 2
I see this is simply the product
of those equilibrium expressions
because I can break that down into each part
and as a result I can find the because I can break that down into each part
and as a result I can find the
equilibrium constant of K 3
by simply multiply K 1 by K 2.