A 2.5 L volume of sodium hydroxide solution was prepared. The titrant was standarized against primary standard oxalic acid dihydrate, H2C2O4*H2O(molar mass is 126.06) if a 0.4774g sample of the prmiary standard consumed 31.94mL of the base solution in reaching the phenophtalein end point, how many grams of sodium hydroxide were required to prepare the 2.5L of solution?

2NaOh(aq)+H2C2O4==>2H2O(l)+Na2C2O4)(aq)

1 answer

H2Ox + 2NaOH ==> Na2Ox + 2H2O

mols Ox = grams/molar mass
mols NaOH required = 2 x mols Ox (from th equation).

M NaOH = mols NaOH/L NaOH/

Then to prepare 2.5L of solution you will need how many mols total? That is M x L = ?
grams NaOH = mols NaOH/molar mass NaOH. You know molar mass and mols, solve for grams.