Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What effect does the presence of an -OH group or an -NH group have on substances?

1. They increase volatility in gaseous states

2. They enhance thermal stability in hydrocarbons

3. They enable halogen bonding and increase solubility in polar substances

4. They decrease reactivity in chemical processes

The correct answer is: They enable halogen bonding and increase solubility in polar substances

The presence of an -OH group (hydroxyl group) or an -NH group (amine group) significantly influences the chemical properties of substances, particularly in regard to their interactions with other molecules. These functional groups are polar due to the electronegativity of the oxygen and nitrogen atoms. This polarity allows molecules containing these groups to form hydrogen bonds with other polar substances, which includes water and other solvents, enhancing their solubility. This ability to hydrogen bond is crucial; hydroxyl groups are often found in alcohols and sugars, which are highly soluble in aqueous solutions due to their interaction with water molecules. Similarly, amine groups, present in amines and proteins, also enhance solubility and play an important role in biological systems. While other factors come into play regarding volatility, thermal stability, and reactivity, the key takeaway is that the presence of -OH and -NH groups allows for significant interaction with polar environments, primarily improving solubility through hydrogen bonding. This is the reason why the correct answer focuses on the ability to enable halogen bonding and increase solubility in polar substances.