ICE tables

[Olivia Kang 3C]

When doing ICE tables, do you always subtract X from the reactants and add X to the products?

[205797525]

Typically, we are given the initial concentrations of the reactant, and in order to get to equilibrium, move in the forward direction to form the products. Therefore when setting up the ICE table, to have the reaction be at equilibrium (since we are setting the concentration ratio to the K value), we subtract the given number of moles from the reactant side, and add the respective amount of moles to (each) product. For example, in the reaction HA -> H+ + A- , we can see there is a 1-1-1 mol ratio between the reactant and its products. Therefore, we would take the initial amount of reaction given (lets say .10M), and subtract x from it (.10M - x), and add the x to both products (x and x).

[805939635]

Sometimes we would subtract 2x or add 2x or any other coefficient, it simply depends on the coefficient of the corresponding compound in the chemical formula. So if we were doing the equilibrium for H2 + I2 (back and forth arrow thing) 2HI, we would subtract x from each of the reactants but would add 2x to HI.

[Ananya Ravikumar 1I]

There is no hard rule, but I guess because reactants are considered the things used up to make new things, the products. The reaction being used is indicated by its concentration going down and the product's concentration going up. A reverse reaction would mean the ICE table shows a -x for what we considered a product in the forward reaction.

[005966393]

It depends on the coefficients, so it might be the coefficient * x, but other than that yeah