[mandy9008]

2NO(g) + Br₂(g)  2NOBr(g)

K_P=28.4

in a reaction mixture at equilibrium, the partial pressure of NO is 111 torr and that of Br₂ is 183 torr.

What is the partial pressure of NOBr?

what i did:
k=[NOBr]²/[NO]²[Br₂]

28.4=x²/(111²)(183)
x=8002.168531torr

the answer is 290 torr.
How do i arrive here?

[Astrokel]

Hmm am i missing something. What is your K_p unit?

[azure]

First off, I must address Astrokel. The equilibrium constant does not have units.
Now for the real question, you are forgetting to factor in your temperature, try using this formula to solve it: 28.4= [(x/(RT))^2]/[(111/RT)^2*(183/RT)]
Just do some algebra to the formula, plug in the correct value (and units) for R, and then plug in your temperature.
Note, this may not necessarily work, because I believe this equation actually factors in Kc as well.

[rabolisk]

Are you sure what you were given was K_p?

[Jorriss]

I'm guessing Br2 is suppose to be liquid.

And K does have units in this case. You get conc^2/conc^3, that has units.

[DevaDevil]

I'm guessing Br2 is suppose to be liquid.

In the question: " in a reaction mixture at equilibrium, the partial pressure of NO is 111 torr and that of Br2 is 183 torr."
so no, it is a gas here.

First off, I must address Astrokel. The equilibrium constant does not have units.

yes it does

Now for the real question, you are forgetting to factor in your temperature, try using this formula to solve it: 28.4= [(x/(RT))^2]/[(111/RT)^2*(183/RT)]

not with K_p.
There is also no temperature given, which would make this unsolvable.


K_p = p_NOBr² / (p_NO² * p_Br2 )

the problem with this is indeed that they did not give any unit with K_p, so you don't know if it is torr^-1, Pa^-1, atm^-1 etc.

based on your given numbers, I do not get to the supposed answer. Can you check the numbers and the question for us again?

[ok123]

You must convert torr to atm for the calculation. Then convert back to torr at the end. (I suppose Kp is based off pressure in atm and that's why.)

[mjc123]

K_p has no units if each pressure is expressed as a multiple of the standard pressure, i.e.

K_p = (P_NOBr/P°)²/{(P_NO/P°)²*P_Br2/P°}

If the standard pressure is 1 atm, the pressure values in torr must be divided by 760.