Problem 93 - Chemistry: The Central Science

Question

Monosaccharides can be categorized in terms of the number of carbon atoms (pentoses have five carbons and hexoses have six carbons) and according to whether they contain an aldehyde (aldo- prefix, as in aldopentose) or ketone group (keto- prefix, as in ketopentose). Classify glucose and fructose in this way.

Step-by-Step Solution

Answer

Both glucose and fructose are hexoses, containing six carbon atoms. Glucose is classified as an aldohexose due to the presence of an aldehyde group, while fructose is a ketohexose because it contains a ketone group.

Step 1: Determine the number of carbon atoms in glucose and fructose

Glucose and fructose are both hexoses, meaning they have six carbon atoms. This is important information for categorizing these monosaccharides.

Step 2: Determine whether glucose contains an aldehyde or ketone group

Glucose has an aldehyde group, which is identified as having a carbon double-bonded to oxygen and single-bonded to a hydrogen atom in its structure. In this case, glucose has a prefix "aldo-" because it contains an aldehyde group.

Step 3: Determine whether fructose contains an aldehyde or ketone group

Fructose has a ketone group, which is identified as having a carbon double-bonded to oxygen and single-bonded to two other carbon atoms in its structure. In this case, fructose has a prefix "keto-" because it contains a ketone group.

Step 4: Classify glucose and fructose according to their number of carbon atoms and functional groups

Glucose is an aldohexose because it has six carbon atoms and contains an aldehyde group. Fructose is a ketohexose because it has six carbon atoms and contains a ketone group.