You have two Erlenmeyer flasks, Flask A and Flask B, each containing 30.00 mL of the samesolution of phosphoric acid of unknown concentration. Flask A:you add a couple of drops of the pH indicator bromocresol green, which changes from yellow to blue when the first proton of phosphoric acid is neutralized.
Flask B: you add a few drops of p-naphtholbenzein, which changes from orange to blue when the second proton is neutralized. You titrate both samples with the same standard solution of sodium hydroxide 0.250 M.
Flask A: you use 12.04 mL of titrant to reach the end point of the titration.
Flask B: you use 23.96 mL of titrant to reach the end point of the titration.

Required:
a. Write and balance the neutralization reaction between phosphoric acid and sodium hydroxide.
b. Write and balance the neutralization reaction between phosphoric acid and sodium hydroxide in which two protons of the phosphoric acid are neutralized (i. e., one of the product is sodium hydrogen phosphate)
c. Determine the molarity of the phosphoric acid from the Flask A data.
d. Determine the molarity of the phosphoric acid from the Flask B data.