P. Chemistry
posted by Tommy on .
The equilibrium 2 SO2(g) + O2(g) 2 SO3(g) has the value K = 2.5 1010 at 500. K. Find the value of K for each of the following reactions at the same temperature.
(a) SO2(g) + 1/2 O2(g) SO3(g)
K =
(b) SO3(g) SO2(g) + 1/2 O2(g)
K =
(c) 3 SO2(g) + 3/2 O2(g) 3 SO3(g)
I attempted to solve this by first finding Kc using the first equation given...I used Kc=K/ (RT)^delta n where delta n= gas productsgas reactants.
I found Kc to be 1.04E12 and then plugged that in to find K for each of the following reactions..however each of my answers was incorrect so I must not be doing this right.

No, that isn't the way to approach it.
For the reaction
A + B = C + D
Given that K = 25
For 2A + 2B = 2C + 2D
K = 25^{2}
For 1/2 A + 1/2B = 1/2 C + 1/2 D
K = 25^{1/2}
For C + D ==> A + B
K = 1/25
etc.
This should help. 
ok. I was able to get the first two but my last one is incorrect. i keep solving it to equal 2.53E16 by making that k= 1/(2.5E10)^1.5 Not sure why this is incorrect..I inverted the K since the rxn is reversed and then used the multiplier as the exponent

oop just realized the third one isn't reversed....DOH! Thanks DrBob

Right. It isn't reversed AND it is to the 3/2 power. .