a) formula generala a alchenei: [tex]C_{n}H_{2n} [/tex]
M=98 kg/kmol => 12*n+1*2n=98 -am folosit masele atomice la C si H
14n=98=>n=7
alchena este C₇H₁₄ - heptena
b) ρ(c.n)=1,25 g/l=[tex] \frac{M}{V_{m} } [/tex]=> M=ρ*Vm=1,25*22,4=28 g/mol
[tex]C_{n}H_{2n} [/tex]
12*n+2n*1=28
14n=28
n=2
alchena este C₂H₄ - etena
c) daca hidrocarbura are NE=1 inseamna ca ai alchena sau cicloalcan(sunt izomeri,in orice caz..au aceeasi formula moleculara)
[tex][tex]C_{n}H_{2n} [/tex][/tex]
ρ=[tex] \frac{M*p}{R*T} [/tex] => ρ*R*T=M*p => M=[tex] \frac{ro* R*T}{p} [/tex]=[tex] \frac{5*0,082*420}{4,1}=42 [/tex] g/mol - vezi ca in calcul ti-am transformat temperatura in grade Kelvin
12*n+2n*1=42
14n=42
n=3
C₃H₆ - propena sau ciclopropan
