The alkanes are a homologous series of hydrocarbons. The alkenes are another homologous series of hydrocarbons containing at least one carbon-carbon double bond.
The tables below show the names and molecular formulas of the first three members of each series:
Table 1: Alkanes
| Name of alkane | Molecular formula |
|---|---|
| ethane | C2H6\text{C}_2\text{H}_6C2H6 |
| propane | C3H8\text{C}_3\text{H}_8C3H8 |
| butane | C4H10\text{C}_4\text{H}_{10}C4H10 |
Table 2: Alkenes
| Name of alkene | Molecular formula |
|---|---|
| ethene | C2H4\text{C}_2\text{H}_4C2H4 |
| propene | C3H6\text{C}_3\text{H}_6C3H6 |
| butene | C4H8\text{C}_4\text{H}_8C4H8 |
What is the general formula for the homologous series of alkanes?
What is the general formula for the homologous series of alkenes? Use the information from Table 2 to help you answer.
State two other features of a homologous series of compounds.
Alkanes are saturated hydrocarbons and alkenes are unsaturated hydrocarbons. State what is meant by the term unsaturated.
Draw the displayed formula for propane, C3H8\text{C}_3\text{H}_8C3H8.
The displayed formula for ethene is:
HH∣∣C=C∣∣HH\begin{array}{ccc} \text{H} & & \text{H} \\ | & & | \\ \text{C} & = & \text{C} \\ | & & | \\ \text{H} & & \text{H} \end{array}H∣C∣H=H∣C∣HDraw the displayed formula for propene, C3H6\text{C}_3\text{H}_6C3H6.
The reaction between ethane, C2H6\text{C}_2\text{H}_6C2H6, and bromine, Br2\text{Br}_2Br2, is a substitution reaction. One product of this reaction is hydrogen bromide, HBr\text{HBr}HBr. State the condition required for this reaction to occur.
Complete the following displayed template to show the other organic product (bromoethane, C2H5Br\text{C}_2\text{H}_5\text{Br}C2H5Br) of this reaction by adding the missing bonds and atoms:
H∣H−C−C∣H\begin{array}{ccccc} & & \text{H} & & \\ & & | & & \\ \text{H} & - & \text{C} & - & \text{C} \\ & & | & & \\ & & \text{H} & & \end{array}H−H∣C∣H−C
