### Calculating Equilibrium Composition

Posted:

**Thu Mar 14, 2019 4:36 am**When using the quadratic equation to calculate the equilibrium composition, how do we know which of the two values is the right one for x?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=49&t=44522

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Posted: **Thu Mar 14, 2019 4:36 am**

When using the quadratic equation to calculate the equilibrium composition, how do we know which of the two values is the right one for x?

Posted: **Thu Mar 14, 2019 7:48 am**

Whichever value that leads to no negative concentrations when plugging back in to the ICE table.

Posted: **Thu Mar 14, 2019 11:30 am**

After you find the x values, you plug it into the ice table. Only one of the values will give an answer that makes sense because the other x value will give a negative equilibrium concentration, which is not possible.