Problem 3 - Chemistry in 30 days

Question

Which statement is true ? (a) The boiling points of diethyl ether and ethyl alcohol are equal (b) Diethyl ether has dipole moment (c) Diediyl ether is highly soluble in water (d) Wiethyl ether is a Lewis acid

Step-by-Step Solution

Answer

Statement (b) is true: Diethyl ether has a dipole moment.

Step 1: Understanding Boiling Point Differences

To determine whether statement (a) is true, consider that diethyl ether and ethyl alcohol are different compounds with distinct properties. Diethyl ether (boiling point approximately 35°C) has a lower boiling point compared to ethyl alcohol (boiling point approximately 78°C). Therefore, the boiling points are not equal.

Step 2: Analyzing Dipole Moments

For statement (b), check whether diethyl ether has a dipole moment. Diethyl ether is a polar molecule due to its C-O bonds, which creates a dipole moment. Therefore, diethyl ether does have a dipole moment.

Step 3: Evaluating Solubility in Water

Evaluate statement (c) on the solubility of diethyl ether in water. Diethyl ether is relatively nonpolar compared to water, which is polar, leading to its low solubility in water. Thus, diethyl ether is not highly soluble in water.

Step 4: Assessing Lewis Acidity

For statement (d), determine if diethyl ether can act as a Lewis acid. A Lewis acid is a species that can accept an electron pair. Diethyl ether is typically not an electron pair acceptor and does not behave as a Lewis acid.

Key Concepts

Boiling Point Comparison

The boiling points of substances can tell us a lot about their molecular properties. For diethyl ether and ethyl alcohol, their boiling points differ considerably. Diethyl ether has a boiling point of approximately 35°C, while ethyl alcohol boils at around 78°C. This difference is due to the hydrogen bonding present in ethyl alcohol, which significantly elevates its boiling point. Diethyl ether, on the other hand, does not exhibit hydrogen bonding to the same extent, resulting in a lower boiling point. This key difference shows how molecular interactions influence boiling points and physical properties.

Dipole Moment

Dipole moment is an indicator of polarity in a molecule. It's the result of uneven distribution of electron density. In the case of diethyl ether, the presence of C-O bonds contributes to its polar character. This creates a net dipole moment due to the difference in electronegativity between carbon and oxygen. Therefore, diethyl ether indeed has a dipole moment, due to its molecular structure and the nature of the bonds it contains.

Solubility in Water

Solubility is a measure of how well a substance dissolves in a solvent such as water. Diethyl ether, being relatively nonpolar, does not dissolve well in water, which is a polar solvent. The ability of a substance to dissolve depends on the principle of "like dissolves like," meaning polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes. Therefore, diethyl ether is not highly soluble in water, owing to its nonpolar character and the polarity of water.

Lewis Acid

To understand if a compound can be considered a Lewis acid, we need to look at its ability to accept electron pairs. A Lewis acid is a chemical species that can accept an electron pair from a Lewis base in a chemical reaction. Diethyl ether, with its oxygen atom, is not typically an electron pair acceptor. Instead, it tends to donate a pair of electrons due to the lone pairs on the oxygen atom. This characteristic prevents diethyl ether from acting as a Lewis acid, classifying it instead more as a potential Lewis base.