Problem 83 - Advanced Problems in Organic Chemistry for Competitive Examinations

Question

Diabetes is detected by testing the urine of a patient usually with (a) Benedict's reagent (b) Nessler's reagent (c) Fenton's reagent (d) Tollen's reagent

Step-by-Step Solution

Answer

Benedict's reagent is used to test for diabetes by detecting sugar in urine.

Step 1: Understanding the Question

First, identify the main purpose of the question: it is asking which reagent is used to detect diabetes by testing urine. This involves understanding how different chemical reagents react with substances present in urine to indicate the presence of diabetes.

Step 2: Analyzing Each Reagent

The question provides four options: Benedict's reagent, Nessler's reagent, Fenton's reagent, and Tollen's reagent. You need to know the specific use of each reagent. Benedict's reagent is used to test for the presence of reducing sugars, which are elevated in the urine of diabetics.

Step 3: Recall the Chemistry Application

Recall that diabetes can lead to glucose spilling over into urine when blood glucose levels are high. Benedict's test is specifically designed to detect sugar in urine, which is a key diagnostic method for diabetes.

Step 4: Choosing the Correct Reagent

Based on the analysis, since Benedict's reagent is used to detect reducing sugars like glucose in urine, which is a common test for diabetes, it is the correct choice.

Key Concepts

Benedict's Reagent

Benedict's reagent is a chemical solution commonly used to test for the presence of reducing sugars. These sugars include glucose, lactose, and fructose, among others. The reagent typically contains copper(II) sulfate, sodium carbonate, and sodium citrate. When mixed with a solution containing reducing sugars and heated, Benedict's reagent undergoes a color change.

This change typically progresses through shades of green, yellow, orange, or red as the concentration of reducing sugars increases. This makes it a useful tool in various applications, particularly in clinical diagnostics.

• Benedict's reagent starts as a clear blue solution.
• A green or yellow precipitate indicates a small amount of reducing sugars.
• An orange or red precipitate suggests a higher amount of these sugars.

In the context of diabetes testing, Benedict's reagent is crucial because it allows for a visual indication of glucose levels in urine. This is particularly important in the detection and management of diabetes, where monitoring glucose levels is essential.

Reducing Sugars Detection

Reducing sugars are a specific type of sugar that can donate electrons to another molecule, reducing it. Many sugars, including glucose, are capable of this electron transfer due to their chemical structure.

The detection of reducing sugars using Benedict's reagent is based on a simple redox reaction. When a reducing sugar is present, it reduces the copper(II) ions in the Benedict's reagent to copper(I) oxide, which is an insoluble red precipitate.

• Not all sugars are reducing sugars. Sucrose, for example, does not show a positive result with Benedict's test because it does not have a free aldehyde or ketone group.
• Common reducing sugars tested in laboratories include glucose and fructose.

By detecting reducing sugars, such as glucose, in a patient's urine, healthcare professionals can assess whether a person may have diabetes, as elevated glucose levels in urine can be an indicator of this condition.

Glucose in Urine

The presence of glucose in urine is medically referred to as glucosuria. In a healthy individual, glucose is filtered by the kidneys and then reabsorbed back into the bloodstream. However, in individuals with diabetes, especially when poorly managed, blood glucose levels can become excessively high.

When this happens, the kidneys may not be able to reabsorb all of the glucose, allowing some to "spill" into the urine.

• Glucose in urine can be an early indicator of diabetes or issues with blood sugar regulation.
• Regular monitoring of urine glucose levels can help manage diabetes more effectively and prevent complications.

Testing urine with Benedict's reagent helps identify glucosuria due to its ability to detect reducing sugars like glucose. This detection is an important diagnostic tool for managing diabetes and monitoring the need for adjustments in diet, medication, or lifestyle changes.