To determine which molecular formula represents an alkene, it's important to understand the defining features of alkenes.
Alkenes are hydrocarbons that contain at least one carbon-carbon double bond. The general formula for alkenes is [tex]\( C_nH_{2n} \)[/tex], indicating that the number of hydrogen atoms is twice the number of carbon atoms.
Let's analyze each given molecular formula:
1. Propene [tex]\(\left( C_3H_6 \right)\)[/tex]
- Here, [tex]\( n = 3 \)[/tex].
- According to the alkene formula [tex]\( C_nH_{2n} \)[/tex], substituting [tex]\( n = 3 \)[/tex] yields [tex]\( H = 2 \times 3 = 6 \)[/tex].
- The formula matches [tex]\( C_3H_6 \)[/tex]. Therefore, Propene is an alkene.
2. Decane [tex]\(\left( C_{10}H_{22} \right)\)[/tex]
- Here, [tex]\( n = 10 \)[/tex].
- According to the alkene formula [tex]\( C_nH_{2n} \)[/tex], substituting [tex]\( n = 10 \)[/tex] yields [tex]\( H = 2 \times 10 = 20 \)[/tex].
- The formula [tex]\( C_{10}H_{22} \)[/tex] does not match [tex]\( H = 20 \)[/tex]. Therefore, Decane is not an alkene.
3. Ethane [tex]\(\left( C_2H_6 \right)\)[/tex]
- Here, [tex]\( n = 2 \)[/tex].
- According to the alkene formula [tex]\( C_nH_{2n} \)[/tex], substituting [tex]\( n = 2 \)[/tex] yields [tex]\( H = 2 \times 2 = 4 \)[/tex].
- The formula [tex]\( C_2H_6 \)[/tex] does not match [tex]\( H = 4 \)[/tex]. Therefore, Ethane is not an alkene.
4. Butane [tex]\(\left( C_4H_{10} \right)\)[/tex]
- Here, [tex]\( n = 4 \)[/tex].
- According to the alkene formula [tex]\( C_nH_{2n} \)[/tex], substituting [tex]\( n = 4 \)[/tex] yields [tex]\( H = 2 \times 4 = 8 \)[/tex].
- The formula [tex]\( C_4H_{10} \)[/tex] does not match [tex]\( H = 8 \)[/tex]. Therefore, Butane is not an alkene.
Among the given molecular formulas, the only one that follows the general rule for alkenes is Propene [tex]\(\left( C_3H_6 \right)\)[/tex].
Thus, the formula that represents an alkene is Propene [tex]\(\left( C_3H_6 \right)\)[/tex].
