Basicity of an acid

this question is not old; i think it'll be ask in the future.

no. of mole of acid = mass / molar mass = 0.75g / 90g.mol^-1 = 0.008333mole
let molecular formula of the acid be HyA, where y is the basicity (i.e. max. no. of ionizable hydrogen per molecule of acid), A(y-) is the anion of the acid after complete neutralization (with negative charge of y).

but wait! you haven't supply the concentration of sodium hydroxide solution.
let C (mol.dm^-3) be the conc. of NaOH sol.
equation of reaction:
HyA + yNaOH ------------> NayA + yH2O

no. of mole of NaOH consumed = volume x molar concentration (mind the unit conversion!)
= (16.67/1000) x C = 0.01667Z mole
mole ratio of HyA:NaOH = 0.008333:0.01667C

however, according to equation, mole ratio of HyA:NaOH = 1:y

then you can figure out what y is, given that you get the value of Z:
0.00833/0.01667C = 1/y



2010-09-20 22:06:01 補充：
"normal" solution probably means 1 M solution. i've checked the wikipedia, but you should check this with your teacher.
C=1, then y=2, ie basicity of acid is 2.