Acids/bases : fraction present in acidic form

[H+] = 6.31 x 10–6

Ka + [H+] 1.74 x 10–5 + 6.31 x 10–6



= 6.31 x 10–6

1.74 x 10–5 + 6.31 x 10–6



= 6.31 x 10–6

23.7 x 10–6



= 6.31

23.7



= 0.26





I’m just confused about the first step.



First, how do you figure out the Ka when you’re only given the pka?



I know that pka = –log Ka, but I don’t know how to reverse that
equation.



And second, how do you figure out the [H+] when you’re only given the
pka and the pH?



Thank you!