The amount of oxalic acid in a sample was determined by the reaction:

2Fe3+ + H2C2O4 + 2H2O----> 2Fe2+ + 2CO2 + 2H3O+.
In an analysis, 10.62g of sample required 36.44 ml of 0.013 M Fe3+. Calculate the %w of oxalic acid in the sample.

•(0.03644L)(0.013 mol/L) = 4.7372x10^-4 mol Fe+3

•(4.7372x10^-4 mol Fe+3)(1 mol H2C2O4 / 2 mol Fe+3) = 2.37x10^-4 mol H2C2O4
•Find the molar mass of H2C2O4 and multiply by the moles of H2C2O4 to get the mass in grams. The mass of H2C2O4 over the mass of the sample, times 100 is the % of H2C2O4.

To calculate the %w (weight percent) of oxalic acid in the sample, you need to determine the amount of oxalic acid present in the sample and then express it as a percentage of the sample mass. Here are the steps to follow:

Step 1: Calculate the number of moles of Fe3+ used in the reaction.
To do this, you need to use the molarity (M) and volume (in liters) of the Fe3+ solution used.
Given:
Molarity of Fe3+ solution (M) = 0.013 M
Volume of Fe3+ solution used (L) = 36.44 mL = 0.03644 L

Number of moles of Fe3+ used = Molarity × Volume
= 0.013 mol/L × 0.03644 L

Step 2: Convert the moles of Fe3+ to moles of oxalic acid.
From the balanced equation, it is clear that the stoichiometric ratio between Fe3+ and H2C2O4 is 2:1. Therefore, the number of moles of oxalic acid is half the number of moles of Fe3+.
Number of moles of oxalic acid = (1/2) × Number of moles of Fe3+

Step 3: Calculate the mass of oxalic acid.
To convert the moles of oxalic acid to grams, you need to use the molar mass of oxalic acid.
Molar mass of oxalic acid (H2C2O4) = 2 × (1.00784) + 2 × (12.0107) + 4 × (15.9994) = 90.0346 g/mol

Mass of oxalic acid (g) = Number of moles of oxalic acid × Molar mass
= Number of moles of oxalic acid × 90.0346 g/mol

Step 4: Calculate the weight percent of oxalic acid in the sample.
The weight percent is the ratio of the mass of oxalic acid to the mass of the sample, expressed as a percentage.
Weight percent of oxalic acid = (Mass of oxalic acid / Mass of sample) × 100

Given:
Mass of sample (g) = 10.62 g

Weight percent of oxalic acid = (Mass of oxalic acid / 10.62 g) × 100

Now, you can substitute the calculated values into the equation to find the weight percent of oxalic acid in the sample.