a. how many molecules of asprin, C 9 h 8 0 4 are there in a 100.0 mg tablets of asprin?
b.how do you calculate the percentage composition of (NH4)2C03.
can someone give me the answers or at least give me a step by step of how getting the answers.
2006-12-18 10:57:03 · 5 answers · asked by Arroyo R 1 in Science & Mathematics ➔ Chemistry
a) Mr of aspirin = 12x9 + 8x1 + 16x4
= 180
100.0mg = 0.1g
No. of mols = mass/Mr
= 0.1/180
= 0.000556mols
Remember to change your mg to g.
b) Excuse me, may I know percentage composition of what? I presume it to be NH4 in the whole compound, if otherwise, you can still follow the formula.
Mr of compound = 2(14 +4x1) + (12 + 16x3)
= 96
Percentage of NH4 = 36/96 x100
= 37.5%
Find the Mr of the whole molecule first, then Mr of your desired composition. Divide accordingly like the above and multiply by 100%.
2006-12-18 11:05:17 · answer #1 · answered by PIPI B 4 · 0⤊ 0⤋
20
2016-05-23 05:35:50 · answer #2 · answered by Anonymous · 0⤊ 0⤋
For a) if you are finding the number of molecules that was found by PIPI in the first answer.
i.e. 0.000556
multiply the number of moles with Avogadro's number = 6.0221415 × 10(to the power 23)
no of molecules=3.3333 X 10 (to the power 20)
2006-12-18 13:52:42 · answer #3 · answered by frozenfire58 2 · 0⤊ 0⤋
Hey, the result for the fist question is 3.97 moles. To calculate it, you just have to divide the weight in grams (250 g) by the Relative Molecular Mass of the substance (HNO3). I will try to find the answers for the other questions!
2006-12-18 11:10:05 · answer #4 · answered by DJ 3 · 0⤊ 0⤋
Arroyo R You are on newspaper!
http://www.osoq.com/funstuff/extra/extra01.asp?strName=Arroyo_R
2006-12-18 11:10:10 · answer #5 · answered by ceh g 1 · 0⤊ 0⤋