Medal and fan
Carbonic acid and the corresponding bicarbonate has a pKa of 6.38. If the pH of the buffer was 6.05, which species would be in higher quantity?

It would be the bicarbonate, correct?

Question

Medal and fan
Carbonic acid and the corresponding bicarbonate has a pKa of 6.38. If the pH of the buffer was 6.05, which species would be in higher quantity?

It would be the bicarbonate, correct?

anonymous · Answer

@aaronq

anonymous · Answer

@Abmon98

aaronq · Answer

use the Henderson-Hasslebalch equation until you are comfortable 

$pH=pKa+log\dfrac{[A^-]}{[HA]}$

$6.05=6.38+log\dfrac{[A^-]}{[HA]}$

$\dfrac{[A^-]}{[HA]}=10^{(6.05-6.38)}=\dfrac{0.4677}{1}$

aaronq · Answer

so there is $\dfrac{0.4677}{1.4677}*100\%=31.9\%$ bicarbonate and 69.1 % carbonic acid.

anonymous · Answer

Why do you divide by 1.467 instead of 1?

aaronq · Answer

because $[A^-]=0.4677$ and $[HA]=1$

so to get the percent you have to divide by the total

anonymous · Answer

Oh okay thankyou!!

aaronq · Answer

no problem!