Mass of the original sample of mixture (g) 1.571 Mass of recovered naphthalene (g) 0.518
Mass of recovered 3-nitroaniline (g) 0.487
Mass of recovered benzoic acid (g) 0.505

Required:
a. % by mass of naphthalene in original sample.
b. % by mass of 3-nitroaniline in original sample.
c. % by mass of benzoic acid in original sample

a. 32.97%

b. 30.99%

c. 32.15%

Explanation:

Percent by mass of the above listed substances in the original mixture can be calculated by dividing the mass of each constituent by the mass of the original mixture, then multiplied by 100.

a. % by mass of naphthalene in original sample = mass of naphthalene/mass of original sample × 100

% by mass of naphthalene = 0.518/1.571 × 100 = 32.97%.

b. % by mass of 3-nitroaniline in original sample = mass of 3-nitroaniline/mass of original sample × 100

% by mass of 3-nitroaniline = 0.487/1.571 × 100 = 30.99%

c. % by mass of benzoic acid in original sample = mass of benzoic acid/mass of original sample × 100

% by mass of benzoic acid = 0.505/1.571 × 100 = 32.15%