To how many significant figures must you determine the percentage of carbon in a drug sample to distinguish cocaine (C17H21O4N) from aspirin (C9H8O4)?
2006-12-20 04:38:36 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
strategy: convert the mole fraction of element in compound to a mass fraction.
procedure: 1)write the subscript X from the formula as (X mol element/1mol compound).
2) Convert moles of elemnet to grams (using the atomic weight).
3)Convert moles of compound to grams(using the molar mass)
4) Multiply by 100%
Plz help me out,i can't seem to know how to use these clues to solve it.
2006-12-20 04:48:29 · update #1
You will need to know the molar masses of the different elements here. They happen to be C = 12, H = 1, O = 16, and N = 14. That means that the molar mass of cocaine is 12*17 + 1*21 + 16*4 + 14*1 = 303 g, and the molar mass of aspirin is 12*9 + 1*8 + 16*4 = 180 g. Meanwhile, the mass of carbon in a mole of cocaine is 12*17 = 204 g, and the mass of carbon in a mole of aspirin is 12*9 = 108. This means that the percentage of carbon in cocaine is 204/303 = 0.6732673267, while the percentage of carbon in aspirin is 108/180 = 0.6. Reported to one significant figure, the percentage in cocaine is 0.7 and the percentage in asprin is 0.6, so this is sufficient to tell them apart.
2006-12-27 05:04:16 · answer #1 · answered by DavidK93 7 · 0⤊ 0⤋
Lick your finger, dab into powder, rub onto gums. Gums will go numb if it is coke. Not dramatically numb like at a dentist office but numb enough to notice.
2006-12-20 04:50:04 · answer #2 · answered by andrew l 1 · 0⤊ 1⤋
That depends highly upon the data provided, and the operations you are doing with it.
2006-12-20 04:44:20 · answer #3 · answered by ? 4 · 0⤊ 1⤋
ooo. ican answer u 2 years later...because then i will have pharmacology...
2006-12-20 04:42:22 · answer #4 · answered by hamid 3 · 0⤊ 1⤋