At a certain temperature, reaction #1 has equilibrium constant (Kc) of 1.9 x10^19. Determine the equlibrium constant for the reaction #2 based on this information at the same temperature.
Reaction #1: 2CCl4(g) + O2(g)<> 2COCl2(g) +2Cl2(g) Kc=1.9 x10^19
Reaction #2: COCl2(g) +Cl2(g)<>CCl4(g) + 1/2 O2(g) Kc =?