Ka of Strong Acids
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Ka of Strong Acids
In the lecture, Dr. Lavelle mentioned that strong acids are not assigned Ka values. Can someone explain why this is?
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Re: Ka of Strong Acids
We assume that strong acids (and bases) dissolve completely. When using the formula to find the Ka of a strong acid, the denominator would be 0, because it completely dissolves, and the result would be undefined.
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Re: Ka of Strong Acids
Strong acids completely dissociate so the Ka, with a denominator of 0 or a very very small number, is either undefined or a very very large number (and it doesn't make sense to assign either of these values to the strong acid).
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Re: Ka of Strong Acids
Image the Ka value as = [H+][Conjugate base]/[acid]
In a strong acid, theoretically all of the acid is disassociated, which means none is left. Therefore, the Ka would have a denominator of zero, which would mean that the Ka would theoretically be infinity.
In a strong acid, theoretically all of the acid is disassociated, which means none is left. Therefore, the Ka would have a denominator of zero, which would mean that the Ka would theoretically be infinity.
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Re: Ka of Strong Acids
We assume strong acids (and bases) to be very large values, but they don't have specific Ka values. In terms of strong acids, the acid would be 100% dissociated, therefore when calculating the Ka, the denominator (A-H concentration) would be zero, hence we would get an extremely large/undefined value.
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Re: Ka of Strong Acids
Since they dissociate completely, there is no need for them to have Ka values. Calculating their Ka would involve dividing by 0, and thus could not be done without getting an undefined value.
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Re: Ka of Strong Acids
Strong acids dissociate completely, therefore there is no Ka value and the denominator is close to zero
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Re: Ka of Strong Acids
Hi! There is no Ka value for strong acids or bases because they disassociate completely. Even if you were to calculate the Ka value, you would have to divide by 0, which would result in you getting an undefined value. Hope this helps!
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Re: Ka of Strong Acids
Strong acids are not given a Ka because they are assumed to almost fully dissociate in water. The Ka values would be so large (since the equilibrium would favor the forward reaction) that it would not be productive to compare the Ka's among strong acids. However, weak acids often favor the reverse reaction, so it would make sense to compare the Ka's.
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