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# equilibria watch

1. how do you calculate the Kc?? please help using the ICE table.
2. (Original post by elena____xo)
how do you calculate the Kc?? please help using the ICE table.
What ICE is initial, changed, and equilibrium.

Initial being the moles you begin with.
Changed being the moles that are reacted.
Equilibrium being the moles remaining when the reaction reaches equilibrium

You're going to be told the starting moles of either the reactants or products or even both.

That's going to be your initial moles.

You're most likely going to be told the moles of one of them at equilibrium.

So that's your equilibrium moles.

To get the moles that was changed, you deduct your equilibrium from your initial moles.
For instance, if I had 2.3 moles of A, and at equilibrium there was only 0.5 A remaining, I know that the reacting moles was 2.3 - 0.5 = 1.8

If you haven't got the equilibrium moles of a species, use the ratios to figure it out.

For instance, in this reaction

I said the reacting moles of A was 1.8. Because there is a 1:2 ratio, I know that the moles of B formed was 1.8 x 2 = 3.6

Once you've got your moles, you can then figure our concentration using the volume given, and its straightforward from there.

NB: Remember that you don't need to calculate concentration if there is an equal number of moles of both sides of the equation.

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