The relative density of alkene vapor in air is 2.414. Derive the molecular formula of the alkene.

To solve the problem, we give a schematic formula for a hydrocarbon – CxHy.
We calculate the molar mass if the density for hydrogen is known:
M (CxHy) = M (air) * D (air) = 29 * 2b414 = 70 g / mol;
Hydrocarbon refers to alkenes, the general formula of which is: CnH2n.
Let’s make the calculations:
CnH2n = 70 g / mol;
12n +2 = 70 g / mol;
12n = 68;
n = 5.6 hence, molecular formula: C5H10;
M (C5H10) = 5 * 12 + 1 * 10 = 70 g / mol.
Answer: the alkene formula is C5H10 (pentene).