jennie experiments with caffeine which containing 49.5% carbon, 5.2% hydrogen, and 16.5% oxygen and 28.8% nitrogen. it has an atomic mass of 194.2 g/mol. what is the formula of caffeine?

Answer 1

First, simply convert your percentages to grams:

C=49.5g= 0.495

H=5.2g= 0.052

O=16.5g= 0.165

N=28.8g= 0.288

The next thing you want to do is to multiply the molecular weight by the percent composition

C=194.2 x .0495 = 96.129

H= 194.2 x .052 = 10.0984

O=194.2 x 0.165 = 32.043

N= 194.2 x 0.288 = 55.9296

Now take each element and divide by its individual atomic weight:

C = 96.129/12.01 = 8.00

H= 10.0984/1.008 = 10

O = 32.043/15.99 =2

N = 55.9296/14.00 = 4

So your formula would be C8H10O2N4 and if I reduce this it will be C4H5ON2