lecture example pKa Ka

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Christineg1G
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lecture example pKa Ka

Postby Christineg1G » Mon Dec 02, 2019 3:55 pm

From the pKa and Ka example done in lecture today, what factors would show that the Ka=6.0x10^-5 is a weak acid and that the equilibrium constant is small?

Brian_Ho_2B
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Joined: Fri Aug 09, 2019 12:16 am

Re: lecture example pKa Ka

Postby Brian_Ho_2B » Mon Dec 02, 2019 4:23 pm

If Ka is provided as some number, then it is most likely a weak acid. Strong acids have Ka values that tend towards infinity because strong acids are COMPLETELY deprotonated while weak acids are partially deprotonated, so Ka values are concrete values that are not towards infinity.

Abby Soriano 1J
Posts: 103
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Re: lecture example pKa Ka

Postby Abby Soriano 1J » Mon Dec 02, 2019 5:13 pm

Anytime a Ka value is given, that alone is a good enough indication that you're being given a weak acid. For strong acids, the Ka value is too big to even be recognized.

Ka = [A-][H+]/[AH]
Due to the complete dissociation of strong acids, the Ka value moves towards infinity since the denominator will just be 0.


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