How many molecules are there in 1 ug of isopentyl acetate, C7H14O2?
Answers:
First find the molar mass of the molecule:
7 M(C) = 7*12.01 = 84.07 g/mol
14 M(H) = 14*1.008 = 14.112 g/mol
2 M(0) = 2*16 = 32 g/mol
Add them up: M(C7H14O2) = 130.182 g/mol
Now use dimensional analysis:
1 µg | 1x10^-6 g/µg | 1/130.182 mol/g| 6.022x10^23 molec/mol
= (1)(1*10^-6)(7.7x10^-3)(6.022x.
= 4.626x10^15molecules
Er, twelvty.
I can't give you a definite answer, you have to do your homework yourself, but here's how you do it
you find out firstly how heavy one mol of isopentyl acetate is, then divide 1ug of the substance with the mass of one mol.
This should give you the amount of mols of this stuff there is (mind you, it might have several decimal places.)
Then, you multiply that number with the Avogrado constant. (6.02*10^23). This should give you the number of molecules there are.
Hope that settles it. Cheers.
The molecular weight is 130 g/mol (7*12+14+2*16). Hence 1 mole weighs 130 g, and 1g contains 1/130 (7.7 x 10^-3) mols. 1 ug (micro gramme) is 1 millionth of 1 g, and hence contains 7.7 x 10^-9 mols.
Each mole contains 6.02 x 10^23 molecules (Avogadro's number). Hence 1ug contains 7.7 x 10^-9 x 6.02 x 10^23 = 4.63 x 10^15 molecules (apx. 4,630,000,000,000,000)
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