Calculate the pH at the second stoichiometric point when 100 mL of a 0.020 M solution of sulphurous acid (Ka1=1.4*10-2, Ka2=6.3*10-8) is titrated with 1.5 M NaOH.
1) What is the most suitable indicator for this titration?
bromocresol green
thymol blue
methyl red
phenol red
methyl orange
phenolphthalein
bromocresol purple
thymolphthalein