ICE table question

[William Cryer 1L]

I was wondering how we know if the "x" in the change row of the ICE table should be positive or negative? Will products always be positive and reactants always negative?

[Sarah_Stay_1D]

I was wondering how we know if the "x" in the change row of the ICE table should be positive or negative? Will products always be positive and reactants always negative?

The reactants are not always negative in an ice table. For example, if you are given values for the products only, you should have a negative x for the products and a positive x for the reactants. The reverse is true if you are only given values for the reactants. There could also be a situation in which you are given an initial value for both products and reactants. In this case you should compare Q to K in order to determine which way the reaction would shift.

[Rachel Formaker 1E]

If you are given initial concentrations and all of them are nonzero, calculate the reaction quotient Q.

If Q<K, the reaction moves toward the products, so the ICE table would have +x on the products side and -x on the reactants side.

If Q>K, the reaction moves toward the reactants, so the ICE table would have -x on the products side and +x on the reactants side.

[Pooja Nair 1C]

When you consider the change in x, you have to think of the way that the quantities are changing in the reaction. Typically you choose one of the compounds in the reaction (based on the known information) to change. For example, if you decrease one of the reactants, all the reactants should decrease by n*x, and the products by n*x (where n is the ratio of moles in the balanced equation). If you decrease the products, the reactants should increase similarly. Just consider what the question is asking you and how it is phrased.

[Lorie Seuylemezian-2K]

Always remember to keep it consistent! If one reactant is decreasing by X then all of them should be decreasing and visa versa!

[juliaschreib1A]

Based on the given information, whether the products are increasing or decreasing, you should be able to deduce whether x is + or -.