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.