Final answer:
To calculate the moles of 3 grams of oxalic acid dihydrate, determine the molar mass and divide the mass of oxalic acid by its molar mass. The molar mass of C2H2O4·2H2O is 126.066 g/mol. Thus, 3 grams is approximately 0.0238 moles.
Step-by-step explanation:
The student asked about the number of moles of 3 grams of oxalic acid dihydrate. This requires calculating the moles using the molar mass of oxalic acid dihydrate as a conversion factor.
First, we need to find the molar mass of oxalic acid dihydrate, which is composed of 2 carbon atoms, 4 hydrogen atoms, 4 oxygen atoms, and an additional 2 water molecules (which has 2 hydrogen atoms and 1 oxygen atom each).
The atomic weights are roughly: Carbon = 12.01 g/mol, Hydrogen = 1.008 g/mol, and Oxygen = 16.00 g/mol. Thus:
Molar mass of C2H2O4·2H2O = 2(12.01) + 2(1.008) + 4(16.00) + 2(2(1.008) + 16.00).
Calculate the molar mass.
Divide the mass of the sample (3 grams) by the molar mass to find the moles.
Now, let's do the calculation:
Molar mass = 2(12.01) + 2(1.008) + 4(16.00) + 4(1.008) + 2(16.00) = 126.066 g/mol
Moles = Mass / Molar mass = 3 g / 126.066 g/mol ≈ 0.0238 mol
Therefore, 3 grams of oxalic acid dihydrate corresponds to approximately 0.0238 moles.