Testing for Glucose



Science Skills: Testing for Glucose

Observation: My two year old tore the label off of one of my 2-Liter bottles of soda. I am allergic to aspartame and cannot do a taste test to determine if the soda is diet or regular. I think (not sure) that I had left the 2-Liter of diet soda on the counter for my husband to take to work.

Problem: Without tasting, what type of soda is the unknown solution: diet or regular?

Research: (Background Information)

• Glucose is a monosaccharide.

• Monosaccharides are the monomers (single unit) of complex carbohydrates.

• Foods high in carbohydrates include breads/cereals/pasta as well as fruits/vegetables.

• Regular soda uses sugar (contains glucose), Diet soda uses aspartame (no glucose)

• A benedict test is used to determine if a sample contains glucose.

Hypothesis: If a benedict test is completed on a known regular soda containing glucose as well as the unknown soda, then the unknown soda will most likely be diet.

Materials: Pick 3 pieces of lab equipment and draw what they look like off to the side of the list.

• 2 test tubes

• test tube rack

• sharpie

• graduated cylinder

• benedict solution in dropper bottle

• beaker

• hot plate

• tongs

• stop watch

Procedure:

1. Label one test tube “G” for glucose and the second test tube “U” for unknown.

2. Place 5 mL of the glucose solution into the test tube marked “G”.

3. Place 5 mL of the unknown solution into the test tube marked “U”.

4. Add 10 drops of benedict solution to each test tube.

5. Record color of liquid in each test tube.

6. Transfer the test tubes to a beaker of boiling water until you observe a color change or two minutes have passed.

7. Remove the test tubes. Observe and record any changes in the color of the solution.

Safety (Prior to Completing Lab): List 2 things you need to do before beginning your lab.

• Why would I put this question after the procedure section of this lab?

________________________________________________________________________________________________________________________________

1. _______________________________________________________

2. _______________________________________________________

Data:

|Test tube |Color of liquid before heating |Color of liquid after heating |

|“G” for Glucose | | |

|“U” for Unknown | | |

Safety (During the completion of the lab): List 2 things you need to do during your lab.

1. _______________________________________________________

2. _______________________________________________________

Conclusion:

1. Was the unknown solution regular or diet soda? Explain. __________________________________________________________________________________________________________________________________________________________________________________________

Safety (After the completion of the lab): List 2 things you need to do after the conclusion of your lab.

1. _______________________________________________________

2. _______________________________________________________

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