Among the following simple organic compounds, which one has the highest boiling point at atmospheric pressure: dimethyl ether (CH3OCH3), methanol (CH3OH), or methane (CH4)?

Introduction / Context:
Boiling point is influenced mainly by the strength and type of intermolecular forces present in a substance. Among small organic molecules, hydrogen bonding, dipole dipole interactions, and London dispersion forces determine how strongly molecules attract one another and therefore how much energy is needed to separate them into the gas phase. This question compares three simple compounds with similar molecular masses but different functional groups and asks you to choose which has the highest boiling point. Understanding this helps in predicting physical properties of organic compounds from their structures.

Given Data / Assumptions:

• Methane (CH4) is a nonpolar molecule with only London dispersion forces.
• Dimethyl ether (CH3OCH3) is a polar molecule with dipole dipole forces but limited hydrogen bonding ability as a hydrogen bond acceptor only.
• Methanol (CH3OH) is an alcohol that can form strong hydrogen bonds because of the O–H group.
• We compare their boiling points at normal atmospheric pressure.

Concept / Approach:
Hydrogen bonding is stronger than ordinary dipole dipole forces, which in turn are stronger than London dispersion forces for molecules of similar size. Methanol has an O–H bond and can form hydrogen bonds both as a donor and an acceptor, leading to strong intermolecular attractions and a relatively high boiling point. Dimethyl ether has an oxygen atom but lacks an O–H bond, so it cannot donate hydrogen bonds, although it can accept them to a limited extent from other molecules. Methane is nonpolar and relies only on weak dispersion forces, so it has the lowest boiling point. Therefore, among the three, methanol has the highest boiling point.

Step-by-Step Solution:
Step 1: Consider methane CH4. It is nonpolar and symmetrical, so the only intermolecular forces are London dispersion forces. Step 2: Consider dimethyl ether CH3OCH3. It has a polar C–O–C linkage and therefore has dipole dipole interactions as well as dispersion forces, but it lacks an O–H group to donate hydrogen bonds. Step 3: Consider methanol CH3OH. It has an O–H bond, allowing molecules to form hydrogen bonds with each other. It also has dipole dipole and dispersion forces. Step 4: Recognise that hydrogen bonding is significantly stronger than simple dipole dipole or dispersion interactions, leading to higher boiling points. Step 5: Conclude that methanol, with its extensive hydrogen bonding, must have the highest boiling point among the given compounds.

Verification / Alternative check:
If you look up approximate boiling points, methane boils around minus 161 degrees Celsius, dimethyl ether around minus 24 degrees Celsius, and methanol around 65 degrees Celsius. These experimental values clearly show that methanol has by far the highest boiling point of the three because more energy is required to break the hydrogen bonds between methanol molecules. Dimethyl ether, with weaker interactions, boils at a much lower temperature than methanol, and methane, with only dispersion forces, boils at the lowest temperature. These real data confirm the theoretical reasoning.

Why Other Options Are Wrong:
Dimethyl ether has a higher boiling point than methane because it is polar, but it still lacks the strong hydrogen bonding network that methanol possesses, so it cannot have the highest boiling point in this set. Methane, being completely nonpolar with only weak dispersion forces, has the lowest boiling point and is a gas at room temperature. The option that all have approximately the same boiling point is clearly incorrect based on the large differences in actual boiling temperatures. The statement that none of these compounds is volatile is wrong because all three are volatile, especially methane and dimethyl ether.

Common Pitfalls:
Students sometimes focus only on molecular mass and neglect the nature of intermolecular forces, leading them to think that compounds with similar formula masses have similar boiling points. Another mistake is to assume that any molecule containing oxygen must have hydrogen bonding of the same strength, without checking for an O–H or N–H bond. To avoid these errors, always check for hydrogen bonding capability and then compare polarity and molecular size when predicting boiling points.

Final Answer:
Among the listed compounds, the highest boiling point is shown by methanol (CH3OH).