Chapter 8: Problem 92
Which of the following is water soluble? A. a saturated fatty acid B. an unsaturated fatty acid C. the side chain on valine D. glucose
Short Answer
Step by step solution
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Hydrophilic vs Hydrophobic
Hydrophilic literally means 'water-loving'.
These substances can form hydrogen bonds with water molecules, making them easily soluble in water.
Examples of hydrophilic groups include hydroxyl (OH) groups, which are common in compounds like glucose.
On the other hand, hydrophobic means 'water-fearing'.
These molecules have non-polar properties, meaning they do not interact well with water.
Fatty acids, for example, have long hydrocarbon chains that are hydrophobic.
These chains repel water and do not dissolve in it.
Understanding these properties helps explain why certain compounds are soluble in water while others are not.
Solubility of Fatty Acids
Saturated fatty acids have single bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.
Despite this difference, both types of fatty acids are generally hydrophobic because of their long hydrocarbon chains.
These chains are non-polar and do not form hydrogen bonds with water.
This lack of interaction with water makes fatty acids insoluble in water.
Additionally, fatty acids tend to aggregate in aqueous environments, forming micelles where the hydrophobic tails point inward and the hydrophilic heads point outward.
This arrangement minimizes the exposure of hydrophobic tails to water, further highlighting their water-insoluble nature.
Glucose Solubility in Water
It contains multiple hydroxyl (OH) groups that can form hydrogen bonds with water molecules.
These interactions make glucose highly soluble in water.
When glucose dissolves, the hydrogen bonds between glucose molecules and water break, allowing glucose molecules to disperse evenly in the solution.
This solubility is crucial for biological processes, as it allows glucose to be quickly transported through the bloodstream to cells where it can be used for energy.
Unlike hydrophobic molecules, glucose does not repel water; instead, it forms strong interactions with it.
This is why, among the given compounds, glucose stands out as being water-soluble.