85.2% yield.
Determine the molar masses of salicylic acid and oil of wintergreen, by first looking up the atomic weights of the involved elements.
Atomic weight carbon = 12.0107
Atomic weight hydrogen = 1.00794
Atomic weight oxygen = 15.999
Molar mass C7H6O3 = 7 * 12.0107 + 6 * 1.00794 + 3 * 15.999
= 138.11954 g/mol
Molar mass C8H8O3 = 8 * 12.0107 + 8 * 1.00794 + 3 * 15.999
= 152.14612 g/mol
Now determine number of moles of each.
Moles C7H6O3 = 16.3 g / 138.11954 g/mol = 0.118013715 mol
Moles C8H8O3 = 15.3 g / 152.14612 g/mol = 0.100561224 mol
Looking at the balanced equation
CH3OH + C7H6O3 ==> C8H8O3 + H2O
it's obvious that for every mole of C7H6O3 used, one mole of C8H8O3 should be produced. But the actual production is lower. To figure the percent yield, just divide the moles produced by the expected production. So
0.100561224 / 0.118013715 = 0.852114721 = 85.2114721%
Since we have 3 significant figures, round to 85.2%
