[astuart]

Hello,

I have a problem with a question from my Physical Chem unit, in which I can't figure out what I'm doing wrong...

Given the equilibrium constant, Kp, of 2.40 x 10-3 at 1000 K for N2(g) + 3H2(g) = 2NH3(g), what is the equilibrium constant for NH3(g) = 1/2N2(g) + 3/2H2(g) at 1000 K?

From what I understand, I need to find the equilibrium constant for the reverse reaction, that has also been halved.

As far as I know, I just need to determine the reciprocal of the initial equilibrium constant (1 / 2.40E-3), and then finding the square root of that (as the reaction was then halved - thus it needs to be put to the power of 1/2).

The question I'm getting is 20.4, when I should be getting 0.024.

Where am I going wrong?

[Schrödinger]

when I should be getting 0.024.

Your answer seems fine to me. 20.4's gotta be right. Does your book say 0.024?

[astuart]

when I should be getting 0.024.

Your answer seems fine to me. 20.4's gotta be right. Does your book say 0.024?

Yep.  It's an online quiz (I'm doing the course through correspondence), and the five options are
a) 2.40E-3
b) 417
c) 0.024
d) 1.20E-3
e) 209

The answer I originally got (20.4) isn't even on the options, so I chose 2.40E-3 and submitted to see what I should have got (0.024 apparently), but that's just confused me more.  I thought I may have been missing something simple, which happens quite often when everything is done via distance education.

If it seems that 20.4 is correct, I'll shoot an email to my lecturer and ask him whether it's an error in the question.

[vex]

Check to make sure that the units haven't been covertly switched on you. Otherwise, I can't imagine why it would be this way.

[astuart]

Check to make sure that the units haven't been covertly switched on you. Otherwise, I can't imagine why it would be this way.

Apparently it must have been an error with the quiz - so all cleared up.  Bit of a pain to waste half an hour trying to figure out where I went wrong though. 

Thanks for the *delete me*