[student]

Hey my question states as following:
if NaOh is in the buret an amount of potassium hydrogen phthalate should be used which will require 20-30ml of 0.05 M of NaOH for neutralization
how many grams of potassium hydrogen phthalate would be required to determine the molarity of the NaOH to four significant figures?
Na0H +HOOCC6H4COOK----GOES TO NaOOCC6H4COOK +H20
the molar mass of the long one is 204.22(HOOCC6H4COOK)

okay so here is my attempt so far, and if you could guide me it would be greatful.
 so i need to figure out the grams first.
and its a 1:1 ratio
imolarity= moles / liters used.
is that 0.05/ or 20 to 30?
when do i used the molecular mass, or do i divide the 0.05/ molecular mass given 204.22
then divide that by the liters? in that case by 20 or 30?

[Borek]

Either do the calculations separately for 20 and fo 30 mL - this will give you a range of mass (something like 0.3-0.4 g of substance - note these are not real values). Alternatively do the calculations for 25 mL of phtalate - this will give a more or less exact value.

[Borek]

This is simple stoichiometry - volume*concentration gives number of moles, substances react 1:1, convert moles of phthalate to mass and you are ready.