K_{p} = K_{c}(RT)^{Δng} or K_{c} = \(\frac{K_p}{(RT)^{\Delta ng}}\)

K_{P} = 2.0 x 10^{10} bar^{-1}

R = 0.083 L bar K^{-1} mol^{-1}

T = 450 K

Δ^{ng} = 2 - 3 = -1

K_{c} = \(\frac{(2.0 \times 10^{10}\,bar^{-1})}{[(0.083\, L\, bar\, k^{-1}\, mol^{-1})\times (450\, K)]^{-1}}\)

K_{c} = (2.0 x 10^{10} bar^{-1}) x (0.083 L bar K^{-1} mol^{-1}) x (450 K)

= 7.47 x 10^{11} mol L^{-1} = 7.47 x 10^{11} M^{-1}.