Question

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?

Accepted Answer

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. 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. 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. 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. 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.

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?

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Key Concepts

Alkanes

Alkenes

Alkynes