Question

1. The chemical formula of caffeine is C8H10N4O2. Determine the percent composition of the molecule.

Show work please

Answer 1

we find the mass for each element in one mole by multiplying the number of atoms in one molecule with the atomic mass

mC=8Ac=8*12=96g

mH=10AH=10*1=10g

mN=4AN=4*14=56g

mO=2AO=2*16=32g

by adding the masses together we find the molar mass of the molecule

M=mC+nH+mN+mO=96+10+56+32=194g/mole

we apply the rule of threes to find the percentage of each element

194g..96gC..10gH...56gN....32gO

100g....a...........b...........c.............d

a=(100*96)/194=49.48%C

b=(100*10)/194=5.19%H

c=(100*56)/194=28.85%N

d=(100*32)/194=16.48%O

Step-by-step explanation: