Propanol, CH3CH2CH2OH, has a molar mass of 60.1 g/mol and a boiling point of 97.4oC. Use intermolecular forces to explain why propanol has a higher boiling point than butane or acetone.
Boiling points depend upon a number of things. For example, intermolecular forces and molar mass as well as symmetry. Propanol has a molar mass of 61. Butane has a molar mass of 58 while acetone has a molar mass of 46. So I don't think this is a good example of IM forces. The answer to the question, in general, is hydrogen bonding present in propanol BUT notice that you would expect a higher molar mass to have a higher boiling point.
To understand why propanol has a higher boiling point than butane or acetone, we need to consider the intermolecular forces present in each compound. Intermolecular forces are forces of attraction between molecules and they directly influence the physical properties of substances, such as boiling point. The main types of intermolecular forces are London dispersion forces, dipole-dipole forces, and hydrogen bonding.
Butane, CH3CH2CH2CH3, is an alkane and consists of only carbon and hydrogen atoms. It has only London dispersion forces acting between its molecules. London dispersion forces are the result of temporary fluctuations in electron distribution, which cause momentary dipoles in molecules and induce a temporary dipole in neighboring molecules. These forces are generally weak and increase with increasing molecular size or molecular weight.
Acetone, CH3COCH3, is a ketone and has a carbonyl group (C=O) present. Acetone molecules can form dipole-dipole interactions due to the polarity of the carbonyl group. Dipole-dipole forces occur when the positive end of one molecule is attracted to the negative end of another molecule. These forces are stronger than London dispersion forces but weaker than hydrogen bonding.
Propanol, CH3CH2CH2OH, is an alcohol, and in addition to London dispersion forces and dipole-dipole interactions, it can form hydrogen bonds. Hydrogen bonding occurs when a hydrogen atom that is covalently bonded to an electronegative atom (such as oxygen, nitrogen, or fluorine) is attracted to another electronegative atom in a different molecule. Hydrogen bonding is the strongest of the intermolecular forces and results in higher boiling points than those of similar compounds that cannot form hydrogen bonds.
In the case of propanol, the presence of a hydroxyl group (OH) allows for hydrogen bonding between neighboring propanol molecules. This additional intermolecular force increases the strength of attraction between the molecules, requiring more energy to break the bonds and convert the liquid into a gas during boiling. Therefore, propanol has a higher boiling point than butane or acetone due to the presence of hydrogen bonding in addition to other intermolecular forces.