Chemistry Question..?

Question

Ok so Aspartame is C14H18N2O5

How many atoms of nitrogen are in 1.2g of aspartame?

If anybody could explain how to do this I would greatly appreciate it.

Thanks.

Answer 1

Molecular weight of aspartame = 294.3 g/mol
Mole of aspartame = 1.2 / 294.3 = 0.00408
Mole of Nitrogen = 2 x 0.00408 = 0.00816
1 mole ==> 6.02 x 10^23
0.00816 x 6.02 x 10^23 = 4.91 x 10^21 atoms of nitrogen

Answer 2

This is solved by calculating how many "moles" of aspartame one has. Chemists don't actually weigh things. They use a very large number and then express weights in terms of this number of atoms. 1 "mole" of aspartame molecules would weigh the sum of its atom's atomic weights. Atomic weights can be looked up in the periodic table. For aspartame, the weight would be:

14*12 + 18*1 + 14*2 + 16*5 = 294 grams/mole

There is 1.2 grams, so this is (1.2/294) moles, or .0041 moles. This expresses the number of aspartame molecules. Each molecule has 2 nitrogen atoms, so there are twice as many moles of nitrogen atoms, or .008 moles. Now, a "mole" is 6E23, or six times ten to the twenty third power. 8 times ten to the negative third power times this number is the number of nitrogen atoms present. 8E-3 * 6E23 = 48E-20, or 4.8E-19

Answer 3

Divide 1.2 by the Mr of aspartame (add up all the Ar values), multiply by 2 for the 2 x N atoms and finally multiply by Avogadro's Number.

Answer 4

MW = 294.3 g/mol

Mole C14H18N2O5 = 0.00408

Mole N = 0.00816
Avogadros constant 6.02 x 10^23

= 4.9 x 10^21 atoms N