Natural Indicator Lab Solution

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Natural Indicators Lab; a Study in pH Levels Using Green Cabbage
pH is the concentration of hydrogen in a substance. It is the scale used to tell how acidic or basic a solution is. The normal pH scale goes zero to fourteen. Zero to about six indicates that the solution is an acid. If the solution is closer to zero it makes it a stronger acid, but if the solution is closer to seven than it is a weak acid. If a solution has a pH of seven then it is neutral. A pH of eight to fourteen indicates that the solution is a base. The farther the pH level is from seven the stronger the base. If the solution has a pH close to seven that indicates that it is a weak base. To determine the pH of certain substances one will use an indicator.
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Obtain about 5 g of flower petals or fruit skin. Note: For small fruits that are not easily peeled, use the entire fruit.
2. Tear, chop, grind, or crush the plant material and place the pieces in a 150-mL beaker.
3. Cover the sample with water or isopropyl alcohol. Use a minimum amount of solvent (approximately 50 mL).
4. After 15 minutes, decant or filter the mixture into a clean, 100-mL beaker. The indicator solution should be clear, not cloudy. Label your beaker and store overnight as your instructor says.

Day 2, Part 2: Determining How pH Affects Your Indicator
5. Your instructor has set up 11 solutions with pH 2-12. Put 5 drops of each substance in your well plates as shown in the picture below. DO NOT CONTAMINATE THE SOLUTIONS!!! NATURAL INDICATOR is left for you to put your plain indicator only.
6. Add 20 drops of your indicator to each of the solutions – standard pH solutions and unknowns. If the colors are very difficult to see, add an extra 5 drops to each.

7. Record your results in a data table like the one below.
Indicator type
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It would change the substances to a clear color to show that it was an acid and then turn the other substances to a pea green color to show that the substance was a base, but that is all the green cabbage would do. In our class the indicator the produced the best results was the red cabbage. The pH scale formed from the red cabbage was the most accurate. The pH levels of the unknown solutions were easily determined by the radish.
The unknown substance for solution one was HCl, it has a pH level of one. Unknown substance two was dishwasher detergent which had a pH level of eleven, indicating that it was a base. Unknown substance three was baking soda which has a pH of nine. Unknown substance four was H2O which has a pH level of six, it is almost neutral. Unknown substance five has a pH of five. Finally, unknown substance six was NH3 and has a pH level of 12 which indicates that it is a strong

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