Question

combustion analysis of an unknown compound provides the following data: 73.5 grams carbon (C), 4.20 grams hydrogen (H) and 72.3 grams chlorine (Cl). What is the percent composition of each element in this compound?

Answer 1

m(C)=73.5 g
m(H)=4.20 g
m(Cl)=72.3 g

mass of compound
m=m(C)+m(H)+m(Cl)

m=73.5+4.20+72.3=150 g

w(H)=100m(H)/m
w(H)=100*4.20/150=2.8%

w(Cl)=100m(Cl)/m
w(Cl)=100*72.3/150=48.2%

w(C)=100-w(H)-w(Cl)
w(C)=100-2.8-48.2=49.0%