[VoiceofGoat]

A 50.00 mL beverage sample is treated with 20.00 mL of 0.01439 M NaOH to neutralize all of the acid in the sample. The resulting solution is then back titrated with 0.0047 M HCl to the phenolphthalein endpoint. It requires 21.73 mL to reach the endpoint. Calculate the % (w/v) of acid in the sample assuming that all of it comes from citric acid.

Not sure how to do this one, any help is appreciated.

[Borek]

You really should at least try, this is quite simple.

How much base was used? How much HCl was added? How much base reacted with the acid present in the beverage?

[VoiceofGoat]

Never mind. Somehow managed to miraculously figure it out.