Question

1,76g hidrocarbura cu densitatea fata de aer 1,522 contin 1,44g carbon. Calculeaza:
a) formula bruta a hidrocarburii;
b) formula moleculara a hidrocarburii.

Answer 1

dgaz=M/Mgaz==>M=dgaz*Mgaz=1.522*28.9=44g/mol

mH=mCxHy-mC=1.76-1.44=0.32g H2

In 1.76g CxHy...........1.44g C........0.32g H2
Atunci in 100g...........x=81.81........y=18.18

C=81.81/12=6.8175 ==>1 atom de C 
H=18.18/1=18.18   ==> 2.66 atomi de H

a) Formula bruta (CH2.66)n

b) Dai o valoare lui n astfel incat sa dea un nr real..

ex : n=1.5 ==> C2H4

sau n=3 ==> C3H8

etc