To determine which molecule is an alkene, we need to know the general formula that defines alkenes. Alkenes are hydrocarbons with at least one carbon-carbon double bond, and they follow the general formula [tex]\( C_nH_{2n} \)[/tex].
Let's analyze each molecular formula to see if it fits the general formula for alkenes:
1. Propene ([tex]\( C_3H_6 \)[/tex]):
- Number of carbons ([tex]\( C \)[/tex]): 3
- Number of hydrogens ([tex]\( H \)[/tex]): 6
- According to the alkene formula [tex]\( C_nH_{2n} \)[/tex], if [tex]\( n = 3 \)[/tex], then [tex]\( 2n = 6 \)[/tex]. Therefore, the molecular formula [tex]\( C_3H_6 \)[/tex] fits the formula for an alkene.
2. Decane ([tex]\( C_{10}H_{22} \)[/tex]):
- Number of carbons ([tex]\( C \)[/tex]): 10
- Number of hydrogens ([tex]\( H \)[/tex]): 22
- According to the alkene formula [tex]\( C_nH_{2n} \)[/tex], if [tex]\( n = 10 \)[/tex], then [tex]\( 2n = 20 \)[/tex]. However, the given number of hydrogens is 22, which does not fit the formula for an alkene.
3. Butane ([tex]\( C_4H_{10} \)[/tex]):
- Number of carbons ([tex]\( C \)[/tex]): 4
- Number of hydrogens ([tex]\( H \)[/tex]): 10
- According to the alkene formula [tex]\( C_nH_{2n} \)[/tex], if [tex]\( n = 4 \)[/tex], then [tex]\( 2n = 8 \)[/tex]. However, the given number of hydrogens is 10, which does not fit the formula for an alkene.
4. Ethane ([tex]\( C_2H_6 \)[/tex]):
- Number of carbons ([tex]\( C \)[/tex]): 2
- Number of hydrogens ([tex]\( H \)[/tex]): 6
- According to the alkene formula [tex]\( C_nH_{2n} \)[/tex], if [tex]\( n = 2 \)[/tex], then [tex]\( 2n = 4 \)[/tex]. However, the given number of hydrogens is 6, which does not fit the formula for an alkene.
From the analysis, only Propene ([tex]\( C_3H_6 \)[/tex]) fits the general formula for alkenes [tex]\( C_nH_{2n} \)[/tex].
Hence, the molecular formula representing an alkene is Propene ([tex]\( C_3H_6 \)[/tex]).
