## X in ICE table

Steven Chau 1B
Posts: 21
Joined: Fri Sep 29, 2017 7:07 am

### X in ICE table

How do we determine if we need to add or subtract x from the reactant?

Nishma Chakraborty 1J
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

### Re: X in ICE table

Hey!

It depends on the direction of the reaction (which you can determine from the equilibrium constant). For instance, if Kc is 2*10^-5, there are more reactants than products, so the system will shift towards the products in order to balance out/reach equilibrium. In that case, you would subtract x from the reactant(s), and add x to the product(s).

Hope this helps :)

Kyra Dingle 1B
Posts: 55
Joined: Fri Sep 29, 2017 7:04 am

### Re: X in ICE table

One way to determine is through what the problem gives you. If only the amount of the initial reactant is given, then the initial concentration of the products would be 0. This then means that the reactants will be consumed to make products until the reaction reaches equilibrium. Since the reactants are being consumed, you would need to subtract x from the reactants in this situation.

Angel Gomez 1K
Posts: 36
Joined: Fri Sep 29, 2017 7:04 am

### Re: X in ICE table

If you were given the concentrations to both products and reactants, you would first need to find Q, which is given by [P]/[R]. Given a value for Kc, you would need to compare Q to Kc and see if it is greater than or less than. If Q is greater, then that means that the reaction would shift toward the reactant side, and you'd subtract x from the product side. If Q was lesser, then that means the reaction would shift toward the product side, and you'd subtract x from the reactant side.

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