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Ariana Murillo 2O
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Postby Ariana Murillo 2O » Tue Nov 29, 2016 4:18 pm

While doing practice problems, when do you take the x out of the denominator?

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Postby Jennifer_Lam_1A » Tue Nov 29, 2016 4:20 pm

I think you're referring to when approximating x. You omit the x in the denominator just to approximate x. Once you find the x, divide it by the molarity given. If it is smaller than 5%, it is a good approximation. I hope that answers your question!

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Postby EmmaSaid3C » Tue Nov 29, 2016 4:23 pm

You can generally take out the x when the k value is less than 10^-5.

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Postby Jeannie_Kim_1I » Wed Nov 30, 2016 8:31 pm

If the k value is equal to 10^-5, would we keep the x in the denominator and use the quadratic equation?

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Postby 904779609 » Wed Nov 30, 2016 8:54 pm

You're in the clear to approximate without using x if it is 10^-5, 10^-6 and so on. If it is 10^-3 you leave x and use the quadratic equation. But if it is 10^-4 you can take out x and to be sure you would then check if you're in the 5% range.

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Postby Skolli20 » Wed Nov 30, 2016 9:19 pm

I also just want to mention what another student told me today at a review session. You can't just blindly approximate if you see the Ka or Kb value is 10^-5. Take the extra 2 minutes and make sure that it is actually 5% because if the initial value is smaller than 10^-5 it will mess up your calculations.

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