-1
$\begingroup$

I need to solve a problem but I can't seem to figure out how to move from the given values to Kp. Here's the question:

2SO2(g) + O2(g) ⇌ 2SO3(g)

ΔrH° = −200 kJ.mol-1 and ΔrS° = −187 J.mol-1.K-1 at 25 °C.

Calculate the temperature at which Kp = 1.

I suppose I'm supposed to calculate ΔG first, and then Kc, but then I'm pretty much stuck.

$\endgroup$

1 Answer 1

2
$\begingroup$

Using the following relations:

$\Delta{G}^⦵ = \Delta{H}^⦵ -T\Delta{S}^⦵$

$K_P = e^{\frac{-\Delta{G}^⦵}{RT}}$

How would you find the temperature at which $K_P = 1$?

$K_P = 1$ when $\frac{-\Delta{G}^⦵}{RT} = 0$, which is when $\Delta{G}^⦵ = 0$

Given what $\Delta{G}^⦵$ must equal, how could you find T?

$\Delta{G}^⦵ = 0 = \Delta{H}^⦵ -T\Delta{S}^⦵ \therefore T = \frac{\Delta{H}^⦵}{\Delta{S}^⦵}$

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.