Question

The relative molecular mass of X hydrocarbon is 72.Find X's molecular formula.
Please help

Answer 1

hydrocarbon = only carbon and hydrogen

C = 12 g/mol
H= 1 g/mol

\(\large C_xH_y\)

The formula needs to make sense, so lets try 5 carbons

5 C = 60

12 H = 12



pentane fits

6 C = 72; doesnt work

4 C = 48

72-48= 24 H's; doens't make sense

Pentane is the only possible formula