posted by anonymous .
1)The chemical formula for aspirin is C9H8O4. What is the mass of 0.40 mol of aspirin? How would I find this?
2)The gram molecular mass of oxygen is 16.0 g right?
3)How would I find the mass, in grams, of 3.01 x 10^23 molecules of water?
1. Add the atomic masses of the elements in the formula. That will be 1 mol. Then 0.4 of that will be 0.4 mol.
2. One mol (of anything) contains 6.02 x 10^23 molecules. So find the mols in 3.01 x 10^23 molecules and that times the molar mass of H2O (obtained by adding the atomic masses) will be that many grams.
Post your work if you get stuck.
1 mol of oxygen atoms has a mass of 16 grams.
water is H2O. One mol of water thus has a mass of approximately 18 grams
The mass of of 3.01 x 10^23 molecules of water is:
(3.01 x 10^23/mol) times the mass of one mol of water =
(3.01 x 10^23/mol) 18 grams.
Now, what is 3.01 x 10^23 divided by 1 mol?
1 mol = approximately 6.022*10^23
1 mol of C9H8O4 contains
9 moles of C, 8 moles of H and 4 moles of O. The mass of 1 mol of aspirine is thus:
(9*12 + 8 + 4*16) grams