Question

Order the three substances above, dimethyl ether, propane, and ethyl alcohol from weakest to strongest total IMF’s. Explain your reasoning. weakest ______ ; ______ ; ______ strongest

Answer 1

From weakest to strongest total intermolecular forces, the order is propane (dispersion forces only), dimethyl ether (dispersion forces and dipole-dipole attractions), and ethyl alcohol (hydrogen bonds in addition to dispersion forces and dipole-dipole attractions), corresponding to their boiling points from lowest to highest.

Step-by-step explanation:

To order dimethyl ether (CH3OCH3), propane (CH3CH2CH3), and ethyl alcohol (CH3CH2OH) from weakest to strongest total intermolecular forces (IMFs), we must consider the types of IMFs present in each substance. Propane is nonpolar and can only exhibit dispersion forces, which are generally the weakest type of IMFs. Dimethyl ether is a polar molecule that exhibits both dispersion forces and dipole-dipole attractions, making its IMFs stronger than propane. Ethyl alcohol has an -OH group, enabling it to form hydrogen bonds in addition to dipole-dipole attractions and dispersion forces, representing the strongest type of IMFs among the three substances.

Therefore, the order from weakest to strongest total intermolecular forces is:

1. Propane (CH3CH2CH3) - exhibits only dispersion forces.
2. Dimethyl ether (CH3OCH3) - exhibits dispersion forces and dipole-dipole attractions.
3. Ethyl alcohol (CH3CH2OH) - exhibits hydrogen bonding in addition to dispersion forces and dipole-dipole attractions.

This order correlates with their respective boiling points, where propane has the lowest boiling point at -42.1 °C, followed by dimethyl ether at -24.8 °C, and ethyl alcohol with the highest boiling point at 78.5 °C. The presence of hydrogen bonding in ethyl alcohol significantly increases its boiling point compared to the other two substances.