PV = niuRT, P = 720mmHg = 720/760 = 0,947 atm
niu = m / miu
=> PVmiu = mRT
=> miu = mRT/PV = 0,93x0,082x(273+87)/0,947x0,5
= 58 g/mol
100% hidrocarbura ..... 82,75% C.. si diferenta.. 17,25% H
58 g/mol ..................... a g C .................................... b g H
= 48 g C = 10 g H
C = 48/12 = 4
H = 10/1 = 10
=> F.m. = C4H10 , butan