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What is a negative result on Benedict's test?

Published in Chemistry 2 mins read

A negative result on Benedict's test indicates that the sample being tested does not contain reducing sugars.

Understanding Benedict's Test

Benedict's test is a chemical test used to detect the presence of reducing sugars, which are sugars that have a free aldehyde or ketone group. These sugars can reduce cupric ions (Cu<sup>2+</sup>) in Benedict's reagent to cuprous ions (Cu<sup>+</sup>), resulting in a color change from blue to green, yellow, orange, or red, depending on the concentration of reducing sugar.

What a Negative Result Means

A negative result means that the solution remains blue after heating, indicating that no reducing sugar is present.

Examples of Reducing and Non-reducing Sugars

  • Reducing sugars: Glucose, Fructose, Lactose, Maltose
  • Non-reducing sugars: Sucrose, Starch

Important Notes

  • Benedict's test is a qualitative test, meaning it only tells you if a reducing sugar is present or absent. It does not provide information about the specific type of reducing sugar or its concentration.
  • The test is sensitive to the presence of reducing sugars, but it can be affected by other factors such as the presence of interfering substances.

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