Question

he Food and Drug Administration (FDA) mandates that all vinegar sold in the United States must have a minimum concentration of 4% acetic acid by mass. Calculate the minimum molarity of acetic acid in vinegar according to this standard. Assume the density of vinegar is the same as for water.

Answer 1

We assume that we have 1 L of vinegar solution. Another assumption, as the problem says, is that the vinegar have the same density as water which is approximative 1000 g/L.

mass of vinegar solution = density × solution volume

mass of vinegar solution = 1000 × 1 = 1000 g

mass of acetic acid = (4 / 100) × solution mass

mass of acetic acid = (4 / 100) × 1000

mass of acetic acid = 40 g

number of moles of acetic acid = mass / molecular mass

number of moles of acetic acid = 40 / 60

number of moles of acetic acid = 0.66

molar concentration of vinegar solution = number of moles of acetic acid / solution volume (L)

molar concentration of vinegar solution = 0.66 / 1 = 0.66 M