Determine the total number of hydrogen atoms: The chemical formula C3H4 indicates that there are a total of 4 hydrogen atoms in the molecule.
Calculate the expected number of hydrogen atoms: In a saturated hydrocarbon (without any double or triple bonds), the general formula for an alkane is CnH2n+2. For a molecule with 3 carbons (n = 3), the expected number of hydrogen atoms would be 2(3) + 2 = 8.
Identify the missing hydrogen atoms: The difference between the expected number of hydrogen atoms (8) and the actual number of hydrogen atoms (4) is 4. This difference represents the number of hydrogen atoms that are missing due to the presence of carbon-carbon double bonds.
Carbon-carbon double bonds and missing hydrogen atoms: Each carbon-carbon double bond accounts for the loss of two hydrogen atoms compared to a single bond. Therefore, the 4 missing hydrogen atoms indicate the presence of 4/2 = 2 carbon-carbon double bonds in the C3H4 molecule.
Hence, the molecule of alkene with the chemical formula C3H4 contains 2 carbon-carbon double bonds.
