Question

H2C2O4.2H2O(s) is primary standard substance. 2.3688g of oxalic acid hydrate were completely neutralized by 42.56ml of NaOH solution. Calculate the molar concentration of the NaOH solution. Write the balanced equation for the reaction.

Answer 1

H2C2O4.H2O + 2NaOH ==> Na2C2O4 + 3H2O

mols H2C2O4.H2O = grams/molar mass
mols NaOH = twice that (look at the coefficients in the balanced equation).
Then M NaOH = mols NaOH/L NaOH.

Answer 2

Oxalic acid dihydrate:
H2C2O4.2H2O(s) same as H6C2O6

H6C2O6(s) + 2NaOH(aq)--> 4H2O + Na2C2O4(aq)

Moles of NaOH:
(2.3688g H6C2O6)*
(1mol H6C2O6/126.064g H6C2O6)*(2mol NaOH/1 mol H6C2O6)
=.037581mol NaOH

Liters of NaOH:
42.56ml= .004256L

NaOH Molarity(molar concentration)
.037581mol NaOH/.004256L NaOH
=8.830M