Quadratic Formula  [ENDORSED]

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Priscilla_Covarrubias_HL
Posts: 16
Joined: Sat Sep 24, 2016 3:00 am

Quadratic Formula

Postby Priscilla_Covarrubias_HL » Fri Dec 02, 2016 9:31 pm

When you solve for the x using the quadratic formula and you get two positive x values....how do you know which one to choose as your correct x?

Chem_Mod
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Re: Quadratic Formula  [ENDORSED]

Postby Chem_Mod » Fri Dec 02, 2016 11:26 pm

One of them will be higher than the initial reactant concentration which is not possible and therefore use the other value.

lorelrodriguez4c
Posts: 9
Joined: Fri Sep 25, 2015 3:00 am

Re: Quadratic Formula

Postby lorelrodriguez4c » Sat Dec 03, 2016 9:38 pm

If you get two positive x values, plug both of them into the Equilibrium row of the ICE box (example: initial concentration - x). One of the x values is going to make the Equilibrium concentration value negative, which is impossible.

Let's say you have x = 0.9 and 1.1

Initial

Change

Equilibrium : 1 - x --> (1 - 0.9) = 0.1
--> (1 - 1.1) = -0.1 which is impossible. Therefore, x has to be 0.9


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