a) M = q·Vm = 1,25g/l ·22,4 l /mol= 28g/mol
alchena ⇔ CnH2n 14n = 28 n = 2 C2H4 (H2C = CH2)
b) T = 420K P = 4,1 atm q = 5g/l
PV = m/MRT PM = qRT M = 5·0,082·420/4,1 = 42 g/mol
14n = 42 n = 3 C3H6 H3C-CH = CH2
c) CnH2n + HOH ⇒ CnH(2n+1) -OH CnH(2n+2)O
Δm = 14n +18 - 14n = 18 g
Δm/M ·100 = 32,14 ⇒ M = 56 g/mol
14n = 56 n = 4 C4H8