# Equilibrium constant problem

1. May 15, 2010

### Spallation

Determine the equilibrium constant, my working is below:

Equilibrium reaction:
[PLAIN]http://img34.imageshack.us/img34/5106/reactiondy.jpg [Broken]

At 730 oC the equilibrium concentrations of reactants and products are:

[H2 (g) ] / mol dm-3 : 2.40 x 10-7

[Cl2 (g)] / mol dm-3 : 2.40 x 10-7

[HCl (g)] / mol dm-3: 5.37 x 10-3

[PLAIN]http://img163.imageshack.us/img163/4485/equationconstant.jpg [Broken]

My answer is wrong but I don't know why, I must have missed something out. Thanks for any explanations I receive.

Last edited by a moderator: May 4, 2017
2. May 15, 2010

### tiny-tim

Welcome to PF!

Hi Spallation! Welcome to PF!

Your arithmetic is wrong … how did you get 2.9 10-5 ?

3. May 15, 2010

### Spallation

I rounded to two significant figures and put it in scientific notation from the answer 0.000028836

Thanks for the welcome :)

4. May 15, 2010

### tiny-tim

erm … 0.000028836 is just the top line!!

5. May 15, 2010

### Spallation

Woah so it is, what a mistake to make, my new answer is 500640625.

6. May 15, 2010

### Studiot

I agree with Tiny Tim your arithmetic is 13 orders of magnitude adrift. This is more than a rounding error.

7. May 15, 2010

### tiny-tim

Woohoo!

(and you were only out originally by about 1014 ! )

8. May 15, 2010

### Spallation

Indeed, how embarrasing! Thank you for the help.