chemistry
posted by abe .
Given the equilibrium constant values:
N2 + 1/2O2 >>> N2O ; kc = 2.7 * 10^18
N2O4>>>>2NO2 kc=4.6*10^3
1/2N2 + O2>>>NO2 kc = 4.1 * 10^9
What is a value of Kc for this reaction?
2N2O + 3O2 >>> 2N2O4

i got 2.72 * 10^17, and got it wrong. i reversed the first by taking the reciprocal, and reversed the 2nd one, times 2 by the last one. added them, square rooted and then doubled. what did i do wrong

equation 1 x 2 and reverse. (1/K_{1}^{2})
equation 2 x 2 and reverse. (1/K_{2}^{2})
equation 3 x 4 as written. (K_{3}^{4} )
K_{c} = (1/K_{1}^{2})*(1/K_{2}^{2})*(K_{3}^{4}) = ??
Check my work. Make sure the equations you have added together gets the equation you want at the end. I think this will do it. I've tried to write superscripts and subscripts but if I missed one of the "turn ons or turn offs" it will be messed up. I'll correct it if it appears to be too difficult to decipher.