Question

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 products-gas 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.

Answer 1

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 = 25²

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.

Answer 2

ok. I was able to get the first two but my last one is incorrect. i keep solving it to equal 2.53E-16 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

Answer 3

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

Answer 4

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