Question

Name and draw structural formulas for all alkenes with the molecular formula \(\mathrm{C}_{5} \mathrm{H}_{10}\). As you draw these alkenes, remember that cis and trans isomers are different compounds and must be counted separately.

Short answer

Answer: There are 5 alkenes with the molecular formula C5H10, including cis and trans isomers. They are: 1. 1-pentene 2. cis-2-pentene 3. trans-2-pentene 4. cis-3-pentene 5. trans-3-pentene

Step-by-step solution

Identify possible carbon chain lengths and arrangements

For the molecular formula \(\mathrm{C}_{5} \mathrm{H}_{10}\), alkenes can have a carbon chain length of 5 carbons, with one double bond at different positions along the carbon chain. Since the molecule has only 5 carbons, the longest possible chain is 5 carbons long.

Draw alkenes with the double bond at different positions

Draw the alkenes with the single double bond at different positions along the 5-carbon chain. There can be a double bond between C1 and C2, C2 and C3, or C3 and C4. We'll refer to these alkenes as 1-pentene, 2-pentene, and 3-pentene, respectively. If the double bond is between C1 and C2 (1-pentene), the compound would not have any cis or trans isomers because the first carbon is connected to two hydrogens.

Draw the cis and trans isomers for each alkene

For 2-pentene and 3-pentene, identify the two isomers for each as they can have cis or trans isomers, and draw their structures: - 2-pentene: Draw cis-2-pentene and trans-2-pentene, where the double bond is between C2 and C3. - 3-pentene: Draw cis-3-pentene and trans-3-pentene, where the double bond is between C3 and C4.

Count and name the alkenes

We have the following alkenes with the molecular formula \(\mathrm{C}_{5} \mathrm{H}_{10}\): 1. 1-pentene 2. cis-2-pentene 3. trans-2-pentene 4. cis-3-pentene 5. trans-3-pentene There are a total of 5 alkenes, including cis and trans isomers, with the molecular formula \(\mathrm{C}_{5} \mathrm{H}_{10}\).