Question

Consider the following equilibrium:

2HI(g) *are in equilibrium with* H2(g) = I2(g) Keq = 81.0

A 2.00L container is initially filled with 4.00 mol HI. Calculate the [HI] at equilibrium.

*I don't know how to put the equilibrium sign on the computer*

Can someone please explain to me how to do this? Thank you in advance!

Answer 1

To do the equilibrium sign you simply use the < the > and == like this <==>. Most of use just use a straight arrow, either --> or ==> and let it go.
(HI) = mols/L = 4.0/2.00 = 2.00M
Set up an ICE chart as below:

........2HI ==> H2 + I2
I.......2.0M.....0....0
C......-2x.......x....x
E......2-2x......x....x

Substitute the E line into Keq expression and solve for x, then 2-2x.

Answer 2

why is it 2-2x? isn't it only just -2x?

Answer 3

oh i get it, it came from the initial... thank you !

Answer 4

That's right. You start with 2.0 (intial), take away -2x (the change) and end up with 2-2x (equilibrium).