How do you determine the concentration of oxalic acid (using unit analysis) when you have the mass? do you need more information?

Concentration is generally expressed in terms of Molarity (M).

Molarity is the number of moles of solute dissolved in one liter of a solvent, i.e.

Molarity = moles of solute(n) / volume of solution (V) (1)

Here the solute is oxalic acid of known mass, m

Molar mass of oxalic acid (H2C2O4) = 90 g/mol

Number of moles, n = mass of oxalic acid/molar mass = m/90 (2)

Substituting for n in equation (1) we get:

M = 'm' gram /(90 gram.mole⁻¹) * ('V' Lit)

M = (m/90*V) mole/Lit

Since the mass of oxalic is known, the volume V is required to complete the molarity/concentration calculation.