Question: how to calculate the mass percent of acetic acid in vinegar?
Answer: Since you are trying to calculate the percentage of acetic acid in vinegar by weight, you need to convert the moles of acetic acid to a mass of acetic acid. You will do this by multiplying the moles of acetic acid with the molecular weight of acetic acid which is 60.0 g of acetic acid in one mole of acetic acid.