what is the expression for keq for: 3a(g)+1b(g)<->2c(g)+2d(g)

Answer 1

If given concentrations, then

Kc = [c]²[d]² / [a]³[b] where [ ] are concentrations

If given partial pressures, then

Kp = (c)²(d)² / (a)³(b) where ( ) are partial pressures

Answer 2

Keq for aA + bB ↔ cC +dD = ([C]^c [D]^d)/ ([A]^a [B]^b). Therefore, Keq for your expression would be:

Keq = ([c]² x [d]²) / ([a]³ x [b])

Please note, "[x]" indicates the concentration of the solute "x". Solids and solvents are not included in the expression as there relative concentration changes are negligible.