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### ICE Chart

Posted: Tue Jan 14, 2020 10:40 pm
When making an ICE chart for a reaction that proceeds in reverse I know the x would be negative but how would you know the reaction is reverse and nor forward? Would it tell you?

### Re: ICE Chart

Posted: Tue Jan 14, 2020 10:48 pm
One possible way to tell is if they gave us the concentrations of products. Then we assume that reactants would be formed and the reverse reaction would take place. Also if Q is given, then we can compare it to the K and see which direction the reaction would proceed in.

### Re: ICE Chart

Posted: Tue Jan 14, 2020 10:51 pm
If you see reverse and forwards reactions as arbitrary, I think it makes ICE tables easier. There is not a universal way to tell which way of a reaction is forward, it just depends on how its written. If ICE tables make sense to you for forwards reactions, just imagine the reverse reaction as the forwards reaction or rewrite the reaction backwards.

### Re: ICE Chart

Posted: Tue Jan 14, 2020 11:32 pm
Problems will usually give you the chemical equation in the order they want the ICE table to be organized, but if not, they will usually give you the initial concentrations of one side of a chemical equation. Organize your ICE table so that those initial concentrations are on the left while the molecules that have an initial concentration of 0 are on the right side. Then, the change row will involve negatives for the molecules that had an initial concentration since you are using that initial concentration while the molecules that started off with no initial concentration will have a change that is a positive variable. Hope this helps!

### Re: ICE Chart

Posted: Tue Jan 14, 2020 11:40 pm
Most times you can tell what direction a reaction will go based on the initial concentrations you are given. If you are only given that you start off with reactants, then the reaction will surely go to the right. If given only products initially, then the reaction will go to the left. If you start with both reactants and products, then you are probably expected to calculate Q in order to compare it to the equilibrium constant and figure out which way the reaction proceeds.

### Re: ICE Chart

Posted: Wed Jan 15, 2020 10:33 am
If you need to calculate Q, then
if Q < K, reaction will proceed in the direction of the products (forward)
if Q > K, reaction will proceed in the direction of the reactants (reverse).
Additionally, if there is a Ka value for the forward reaction, then 1/Ka would be the equilibrium constant for the reverse reaction.