for the titration of n.89g of an uk diaprotic acid with .2500 N sodium hydroxide, it took 35.5 mL to reach the phenolphthalein endpoint, calculate the molar mass.
I expect that is diprotic acid.
The problem doesn't say but I assume the phenolphthalein end point will titrate BOTH H ions.
mL x N x mew = grams where mew is milliequivalent weight.
Substitute and solve for mew.
Convert to equivalent weight.
Then equivalent weight = molar mass/2