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How to Make a Turmeric PH Paper

Curcumin, a vibrant yellow polyphenol in turmeric, is a pH indicator. Curcmin is yellow in acidic of neutral solutions, but becomes red when exposed to an alkaline solution. The color change in curcumin occurs between a pH of 7.4 and 8.6. The pH is a measure of the acidity, or the concentration of hydrogen ions relative to hydroxide ions, of an aqueous solution.

Things You'll Need

  • Turmeric powder
  • Alcohol
  • Disposable cups and plates
  • Absorbent paper
  • Baking soda
  • Vinegar
  • Water
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Instructions

    • 1

      Add 2-3 teaspoons of turmeric powder to the bottom of a plastic cup. Be cautious with turmeric, as it will stain clothes or other porous materials.

    • 2

      Cover the turmeric powder with about an inch of alcohol and stir. Although methanol is preferred, concentrated ethanol or isopropyl alcohol can also be used. This dissolves some of the curcumin from the turmeric, separating it from the rough powder of the turmeric root.

    • 3

      Place a small piece of absorbent paper on a disposable plastic plate. Unbleached toilet paper or paper towels without dye can also be used.

    • 4

      Allow turmeric powder to settle at the bottom of the cup.

    • 5

      Pour only the now-yellow alcohol over the paper in the plate. Be very cautious not to spill the alcohol or allow much turmeric powder to be poured over the paper.

    • 6

      Allow the paper to dry and cut into strips.

    • 7

      Prepare one cup with four teaspoons of water; one cup with two teaspoons of water and two teaspoons of vinegar; and one cup with two teaspoons of water and two teaspoons of baking soda. These solutions are neutral, acidic and alkaline, respectively. This will allow you to test how the turmeric strips react to different pH solutions.

    • 8

      Dip strips of curcumic-dyed paper into the three test solutions and observe. The paper should remain yellow in the vinegar and water but turn red in the baking soda solution.

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