example
•#1: 75.0-g sample = 20.5 g C, 54.5 g O
•#2: 135.0-g sample = 67.5 g C, 90.0 g O
•are they the same?
•(20.5 g C / 75.0 g total ) • 100 = 27.3% C
•(67.5g C / 135.0 g total ) • 100 = 50.0% C
•they are not the same!
•