Question

Aldonic acids are compounds that: (A) can be oxidized, and therefore act as reducing agents. (B) can be reduced, and therefore act as reducing agents. (C) have been oxidized, and have acted as reducing agents. (D) have been oxidized, and have acted as oxidizing agents.

Short answer

The correct answer is (C): Aldonic acids have been oxidized and have acted as reducing agents.

Step-by-step solution

Understand Aldonic Acids

Aldonic acids are derived from aldoses (simple sugars) by oxidation of the aldehyde group to a carboxyl group.

Identify Oxidation and Reduction

Oxidation involves the loss of electrons and increase in oxidation state. Reduction involves the gain of electrons and decrease in oxidation state.

Determine the Role of Aldonic Acids

Since aldonic acids are formed through the oxidation of aldoses, the aldehyde group is converted into a carboxyl group, implying these acids have been oxidized.

Evaluate Options

Based on the information: (A) is incorrect because aldonic acids cannot be oxidized further. (B) is incorrect because aldonic acids cannot act as reducing agents. (C) is correct because aldonic acids have been oxidized. (D) is incorrect because oxidizing agents would be reduced, not oxidized.

Key concepts

oxidation and reduction

When we talk about chemical reactions, oxidation and reduction are key concepts to understand. Oxidation is the process in which a substance loses electrons and its oxidation state increases. On the other hand, reduction is when a substance gains electrons and its oxidation state decreases.

Think of it like this: Oxidation is losing (OIL) electrons and reduction is gaining (RIG) electrons. They often occur together in redox reactions where one substance is oxidized and another is reduced. For example, in the formation of aldonic acids from aldoses, the aldehyde group of the sugar (aldose) is oxidized to a carboxyl group, meaning the aldehyde loses electrons and its oxidation state increases.

This process is crucial in many biochemical pathways. Remember that oxidizing agents are substances that gain electrons and are reduced in the process, whereas reducing agents give away electrons and are oxidized.

aldoses

Aldoses are a type of simple sugar with an aldehyde group. Examples include glucose and galactose. These sugars are essential in biology as they serve as energy sources and building blocks for more complex carbohydrates.

In aldoses, the presence of the aldehyde group means they can undergo oxidation. When an aldose is oxidized, its aldehyde group is typically transformed into a carboxyl group, resulting in the formation of an aldonic acid. For instance, when glucose is oxidized, it forms gluconic acid.

It's important to know that this transformation changes the chemical properties of the sugar. While the aldose can act as a reducing agent because it can donate electrons during the oxidation process, the resulting aldonic acid has already given away its electrons and usually cannot be further oxidized or act as a reducing agent.

oxidizing and reducing agents

In chemical reactions, we often encounter oxidizing and reducing agents. These agents play critical roles in driving the reactions forward.

Oxidizing agents are substances that accept electrons and are reduced in the process. Due to their ability to gain electrons, they are essential in reactions where other substances need to be oxidized. Common oxidizing agents include substances like oxygen, chlorine, and potassium permanganate.

Reducing agents, conversely, donate electrons and are oxidized during the reaction. They enable other substances to be reduced. Examples include hydrogen, sodium, and certain organic compounds.

Understanding these agents is essential when studying redox reactions. In the context of aldonic acids, remember that these compounds have already acted as reducing agents when they were sugars (aldoses) and cannot typically act as reducing agents anymore because they have completed their oxidation.