The flask shown here contains 0.3999 of acid and a few drops of phenolphthalein

Question

The flask shown here contains 0.3999 of acid and a few drops of phenolphthalein indicator dissolved in water. The buret contains 0.310 M NaOH. What volume of base is needed to reach the end point of the titration? Number 32 mL base What is the molar mass of the acid (assuming it is diprotic and that the end point corresponds to the second equivalence point)? 111.9 g/mol You may have gone past the end point of the titration, or you may be reading the volume in the buret incorrectly. Be sure to stop the titration after a single drop from the buret causes the solution in the flask to turn pink and stay pink. Add base to the solution until it just turns pink. You may Number need to reset the titration if you go past the end point.

Explanation / Answer

vol of the base = 23.5 ml

no .of moles of base = 0.31*23.5*10^-3 = 0.007285

moles of acid required = 0.007285/2 = 0.0036425 moles

mol.wt = wt/no.of moles

mol.wt = 0.399/0.0036425 = 109.54 gm /mol

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