5% rule clarification

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5% rule clarification

Postby Ami_Pant_4G » Mon Jan 20, 2020 9:33 am

When approximating for a small Ka, should we always calculate % ionization to ensure it is lower than 5%? Thanks in advance.

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Re: 5% rule clarification

Postby Christineg1G » Mon Jan 20, 2020 9:48 am

If k<10^-3 you can attempt an approximation. To ensure the validity of your approximation, you should check by dividing the x value you received over the initial concentration. If this value is less than 5%, your approximation is valid.

Jessica Chen 2C
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Re: 5% rule clarification

Postby Jessica Chen 2C » Mon Jan 20, 2020 11:25 am

Yes, if you approximate for a small x value (when K<10^-3), you have to check that the value of x is less than 5% of the initial concentration in order for the approximation to be valid.

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