Question

The suitable indicator in the above titration will be:

• A. phenolphthalein
• B. methyl orange
• C. litmus
• D. bromothymol blue

Answer 1

The correct option is B methyl orange

When $N{a}_{2}C{O}_3$ titrated against $HCl$ following reaction takes place:

$N{a}_{2}C{O}_3+HCl⟶NaHC{O}_3+NaCl$

$NaHC{O}_3+HCl⟶H_{2}C{O}_3+NaCl$

As we know that $HCl$ is strong acid therefore overall reaction taking place in acidic medium and we need an indicator which turns into ionic form at lower $pH$ like methyl orange $(pHrange3.2-4.4)$