Trying to ask a question here and anything pasted into the description is double-spaced - will post my question proper later ...

Running the following partial script gives me results as expected

Kw = 1*10^-14;

Ca = 0.1;

Va = 10;

pKa = 4.757;

Ka = 10^-pKa;

Cb = 0.1;

pKb = 0.2;

Kb = 10^-pKb;