My PBL Project
Part A: Study
INTRODUCTION
What colors will be produced when indigo carmine is added to a solution of dextrose and sodium hydroxide?
-Description: In this experiment, the student will shake a flask with the solution in it to yield the colors of a signal.
MATERIALS
-Erlenmeyer flask, 500-mL with stopper
-Graduated cylinder, 100-mL
-Graduated cylinder, 10-mL
-Dextrose solution, 0.13M, 100 mL
-Sodium hydroxide solution, 1.0M, 100 mL
-Indigo carmine solution, 1%, 10 mL
PROCEDURE
1 - Prepare the solutions using quantities shown or prepared solutions may be purchased.
Indigo carmine solution – 1.0 g of indigo carmine dissolved in 10 mL of distilled water
Dextrose solution – 24.0 g of dextrose dissolved in distilled water to make 1 L of solution.
Sodium hydroxide solution – 40.0 g of NaOH pellets dissolved
in distilled water to make 1 L of solution.
2 - Place 100 mL of dextrose solution and 100 mL of sodium hydroxide solution in a 500-mL Erlenmeyer flask.
3 - Add 10 mL of indigo carmine indicator solution to the flask and insert stopper firmly.
4 - Allow the solution to sit till the color changes completely yellow.
5 - Shake the flask and observe the color change from yellow to red to green and then back to yellow.
6 - Discuss your observations, inferences, explanations and extensions.
SCIENTIFIC PRINCIPLE
This project is based on the scientific principles of reverse reactions and oxidization. In this experiment, two reactions (forward and backward) are occurring at the same time, as observed by the various color changes after different actions (shaking or setting) due to different levels of oxygen.
SAFETY REGULATIONS
This activity requires the use of hazardous chemicals and has the potential for hazardous reactions. Wear chemical splash goggles, chemical-resistant gloves, and a chemical-resistant apron. Review current Material Safety Data Sheets for additional safety, handling, and disposal information.
OBSERVATIONS AND DATA
For this experiment, I shook a flask containing sodium hydroxide, dextrose, and the indicator indigo carmine to observe the color changes that occurred - from yellow to red to green. After I added the indigo carmine to the flask, the solution was yellow. After shaking the flask continuously for a few seconds and observing the presence of bubbles, the solution in the flask switched from the color yellow to red to green, as a result of more oxygen. After setting it down, the color transitioned back to yellow, as the amount of oxygen was decreased. The same cycle occurred during every trial of the test.
EXPLANATION
In this experiment, two reactions (backward and forward) are occurring simultaneously. The forward reaction is where the color of the solution changes from yellow to red to green, and the backward reaction is where the color changes from green to red to yellow, reversing the original reaction. The indigo carmine indicator changes color as a result of the changing amounts of oxygen in the solution. At first, the solution is yellow in color, but when the flask is shaken, oxygen dissolves into the solution, oxidizing the indicator and changing the color of the solution to red. When the flask is shaken again, the levels of oxygen increase more, oxidizing the indicator further and causing it to turn green. When the solution is left alone, the oxygen concentration drops because of a reaction with the dextrose, so the solution will turn back to its original yellow color.
Part B: Investigation
Driving Question 1: What colors will be produced when methylene blue is added to a solution of dextrose and sodium hydroxide?
MATERIALS
-Erlenmeyer flask, 500-mL with stopper
-Graduated cylinder, 100-mL
-Graduated cylinder, 10-mL
-Dextrose solution, 0.13M, 100 mL
-Sodium hydroxide solution, 1.0M, 100 mL
-Methylene blue solution, 1%, 10 mL
PROCEDURE
1. Prepare the solutions using quantities shown or prepared solutions may be purchased.
-Methylene blue solution – 1.0 g of methylene blue dissolved in 10 mL of distilled water
-Dextrose solution – 24.0 g of dextrose dissolved in distilled water to make 1 L of solution.
-Sodium hydroxide solution – 40.0 g of NaOH pellets dissolved in distilled water to make 1 L of solution.
2. Place 100 mL of dextrose solution and 100 mL of sodium hydroxide solution in a 500-mL Erlenmeyer flask.
3. Add 10 mL of methylene blue indicator solution to the flask and insert stopper firmly.
4. Allow the solution to sit till the color changes completely yellow.
5. Shake the flask and observe the color change from yellow to red to green and then back to yellow.
6. Discuss your observations, inferences, explanations and extensions.
Driving Question 2: What colors will be produced when indigo carmine is added to a solution of dextrose and potassium hydroxide?
MATERIALS
-Erlenmeyer flask, 500-mL with stopper
-Graduated cylinder, 100-mL
-Graduated cylinder, 10-mL
-Dextrose solution, 0.13M, 100 mL
-Potassium hydroxide solution, 1.0M, 100 mL
-Indigo carmine solution, 1%, 10 mL
PROCEDURE
1. Prepare the solutions using quantities shown or prepared solutions may be purchased.
-Indigo carmine solution – 1.0 g of indigo carmine dissolved in 10 mL of distilled water
-Dextrose solution – 24.0 g of dextrose dissolved in distilled water to make 1 L of solution.
-Potassium hydroxide solution – 40.0 g of NaOH pellets dissolved in distilled water to make 1 L of solution.
2. Place 100 mL of dextrose solution and 100 mL of potassium hydroxide solution in a 500-mL Erlenmeyer flask.
3. Add 10 mL of indigo carmine indicator solution to the flask and insert stopper firmly.
4. Allow the solution to sit till the color changes completely yellow.
5. Shake the flask and observe the color change from yellow to red to green and then back to yellow.
6. Discuss your observations, inferences, explanations and extensions.