Question

Calculate the mass of oxalic acid dihydrate needed to prepare 500.0 ml

Answer 1

Moles= molarity x liter
=0.2500 M x 0.500 L
= 0.1250 mol

mass C2H2O4 . 2H2O = 0.1250 mol x (126.068 g / 1 mol)
=15.76 g 

Answer 2

This question is incomplete.

The complete question is: Calculate the mass of oxalic acid dihydrate $C_2H_6O_6.2H_2O$ needed to prepare 500.0 mL of 0.2500 M oxalic acid solution.

Answer: 15.75 grams

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

Molarity = 0.2500 M

n= moles of solute  = ?

$V_s$ = volume of solution in ml = 500.0 ml

$0.2500=\frac{n\times 1000}{500.0}$

$n=0.1250$

Mass of oxalic acid dihydrate = $moles\times {\text {Molar Mass}}=0.1250\times 126.07g/mol=15.75g$

Therefore, the mass of oxalic acid dihydrate needed to prepare 500.0 ml is 15.75 grams