In Table 7.2, what is the smallest alkane, the smallest terminal alkene, and the smallest terminal alkyne that are liquids at room temperature, which is generally taken to be 20 °C to 25 °C?

Verified step by step guidance

1. Step 1: Understand the question. The problem asks for the smallest alkane, terminal alkene, and terminal alkyne that are liquids at room temperature (20 °C to 25 °C). This requires knowledge of the physical states of hydrocarbons and their boiling points.
2. Step 2: Recall the general trend in boiling points of hydrocarbons. As the molecular weight (or chain length) of hydrocarbons increases, their boiling points increase due to stronger London dispersion forces. Smaller hydrocarbons (with fewer carbons) tend to be gases at room temperature, while larger ones are liquids or solids.
3. Step 3: Identify the smallest alkane that is a liquid at room temperature. Alkanes are saturated hydrocarbons with the general formula \( C_nH_{2n+2} \). Use a reference table or boiling point data to find the smallest alkane with a boiling point above 20 °C but below 25 °C.
4. Step 4: Identify the smallest terminal alkene that is a liquid at room temperature. Terminal alkenes are unsaturated hydrocarbons with a double bond at the end of the chain, having the general formula \( C_nH_{2n} \). Again, consult boiling point data to find the smallest terminal alkene with a boiling point in the specified range.
5. Step 5: Identify the smallest terminal alkyne that is a liquid at room temperature. Terminal alkynes are unsaturated hydrocarbons with a triple bond at the end of the chain, having the general formula \( C_nH_{2n-2} \). Use boiling point data to determine the smallest terminal alkyne that is a liquid at 20 °C to 25 °C.

Key Concepts

Alkanes

Alkanes are saturated hydrocarbons consisting only of carbon and hydrogen atoms, connected by single bonds. They follow the general formula CnH2n+2, where 'n' is the number of carbon atoms. The smallest alkane is methane (CH4), which is a gas at room temperature, but as the number of carbon atoms increases, alkanes can become liquids, with pentane (C5H12) being the smallest liquid alkane.

Alkenes

Alkenes are unsaturated hydrocarbons that contain at least one carbon-carbon double bond, following the general formula CnH2n. The smallest terminal alkene is ethylene (C2H4), which is a gas at room temperature. However, as the carbon chain length increases, alkenes can also exist as liquids, with 1-hexene (C6H12) being the smallest liquid terminal alkene.

Alkynes

Alkynes are unsaturated hydrocarbons characterized by at least one carbon-carbon triple bond, adhering to the general formula CnH2n-2. The smallest terminal alkyne is acetylene (C2H2), which is a gas at room temperature. As with alkenes, longer-chain alkynes can be liquids, with 1-butyne (C4H6) being the smallest liquid terminal alkyne.