Calculating the equilibrium constant?

Question

For the following equilibrium expression and its value, write a balanced equation for the reverse reaction and calculate the value of the equilibrium constant for the reverse reaction, K’:

[C2H6][H2] = 9.5 x 10-13

[CH4]

Note: The [CH4] is UNDER the other two molcules, meaning it's divided... Just in case anyone was wondering.

Answer 1

[CH4]^2

[C2H6][H2]   =       (1 / 9.5x10^-13^2)

2CH4=C2H6 + H2

Um..I think this is what you wanted?

Ka has an exponential relationship with stoiciometry so square Ka^2 before dividing into 1!! You divide into 1 when you reverse a reaction. So Ka changes to 1/Ka