chemistry, stoicheometry?

Question

Aspirin has the formula C9H8O4. How many moles of aspirin are in a tablet weighing 601 mg?

Answer 1

1)calculate atomic weight of the molecule
9 carbon+8 hydrogen+4 oxygen=
(12)(9)+(1)(8)+(16)(4)=180 g/mole

2)convert 601 mg to grams (notice it cancels out the units...that's one of the key things to chemistry...look to cancel out units to get the unit u want.)
601 mg/(1000 mg/g)= 0.601 grams

3)cancel the grams...
0.601 grams/(180 g/mole)= 3.33 x10 to the -3 power moles

(sorry, it's a little hard to visualize the units canceling out here, but i can't depict it any better here. to see it better...lay out everything like a fraction...0.601 g over 1 and have that one multiply 1 mole over 180 g. when i wrote 180 g/mole, keep in mind that is also saying a ratio...180 g to 1 mole....so that's how u can just flip it around...to 1 mole/180 g.)

Answer 2

we can calculate the number of moles by dividing the given mass of compound by molecular mass.The answer of your question is 3.33.