Question

Aqueous solutions of isopropyl alcohol are commonly sold as rubbing alcohol. The boiling point of isopropyl alcohol is 82.4 °C. It evaporates readily from the surface of the skin. Ethylene glycol (CH2OHCH2OH) is sold as antifreeze/antiboil. The boiling point of ethylene glycol is 198 °C. The molecular masses of isopropyl alcohol and ethylene glycol are similar. Provide an explanation for the observed difference in their boiling points.

Answer 1

The difference in boiling points between isopropyl alcohol and ethylene glycol is due to the stronger intermolecular hydrogen bonds in ethylene glycol, requiring more energy to break than the weaker forces in isopropyl alcohol.

Step-by-step explanation:

The observed difference in boiling points between isopropyl alcohol and ethylene glycol, despite their similar molecular masses, can be attributed to the types of intermolecular forces present in each liquid. Ethylene glycol has a higher boiling point due to the presence of strong hydrogen bonding interactions between its molecules, which are more effective at holding the molecules together, thereby requiring more energy to evaporate. In contrast, isopropyl alcohol has weaker interactions such as van der Waals forces and some hydrogen bonding, which are easier to overcome and thus have a lower boiling point.

Answer 2

This is due to more hydrogen bonding in ethylene glycol than it is in isopropyl alcohol

Step-by-step explanation:

The boiling point of isopropyl alcohol is 82.4 °C it contains only a single OH group, hence intermolecular hydrogen bonding is solely responsible for it's boiling point, whereas Ethylene glycol (CH2OHCH2OH) contains 2-OH group and both intermolecular and intramolecular hydrogen bonding are responsible for the higher boiling point of ethylene glycol at 198 °C.