Question

For the experiment of titration, what are the two indicators preferred?

Answer 1

✍Methyl orange and Phenolphthalein are the two important indicators..✔✔

Answer 2

I would pick either phenophthalein or methyl-orange. Phenophthalein will change for the first protonation:

Na2CO3 + HCl = NaHCO3 + NaCl

Methyl-orange will change for the second protonation:

NaHCO3 + HCl = H2CO3 + NaCl

H2CO3 = H2O + CO2

Either titration will tell you the amount of Na2CO3 you have.