Method for Concentration of Potassium Permanganate

Potassium permanganate is a chemical oxidizer available to the general public in the form of crystals. It is used during water treatment to remove color and odor, some metals, and microorganisms, such as algae. Potassium permanganate is water-soluble, creating a pink-to-purple tint when mixed. It is available at pure strength through chemical dealers and at lower grades through home supplies stores. Potassium permanganate can cause eye and skin irritation, and respiratory problems, and it is fatal if swallowed, therefore proper protective equipment is needed when handling it. The method of concentration for potassium permanganate depends on the quantity needed.

Things You'll Need

• Potassium permanganate
• Gloves
• Goggles
• Scale
• Distilled water
• 1000 mL container or volumetric flask

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Instructions

Strengths

• 1

  Use this formula to calculate the appropriate concentration of potassium permanganate needed to treat a large volume of water.

  Amount of Chemical = Volume x Conversion Factor x Treatment Rate

• 2

  Let "Amount of Chemical" equal the amount of grams needed to treat a large volume of water. For example a fish pond.

• 3

  Let "volume" equal the volume in units (gallons, cubic feet, acre feet) of the water body. For example, the volume might be a 250-gallon pond.

• 4

  Determine the "conversion factor." The conversion factor depends on the chemical and volume units that you are working with. For example, converting grams to gallons = 0.0038, pounds to acre-foot = 2.72, and grams to cubic-foot = 0.0283.

• 5

  Let "treatment rate" equal the final concentration of potassium permanganate in the pond after the chemical is added. In our example of the 250-gallon pond, the treatment rate is 2 milligrams per liter or a concentration of 2 parts per million.

• 6

  Solve for the "amount of chemical." For example, Amount of Chemical = 250 gallons x .0038 x 2 milligrams per liter = 1.9 grams. Therefore 1.9 grams of potassium permanganate is needed to treat a 250-gallon pond at a concentration of 2 milligrams per liter.

Dilutions

• 7

  Use the C1V1 = C2V2 formula to dilute a 1000 parts per million of potassium permanganate. A smaller concentration is needed for smaller volumes of water, such as a garden pond. C stands for concentration, and V for volume.

• 8

  Let "C1" equal the original concentration of the solution. For this example, 1000 parts per million will be used.

• 9

  Let "V1" equal the volume to be diluted. In this example, 50 milliliters of the 1000 parts per million needs to be diluted.

• 10

  Let "C2 "equal the final concentration after the dilution. The final concentration can be a certain amount or an unknown. In our example, the final concentration needs to be 100 parts per million.

• 11

  Let "V2" equal the final volume. The final volume can be a known or unknown amount. For our example, the final volume will be unknown.

• 12

  Write out the formula. For example, C1V1 = C2V2 is now (1000 parts per million)(1000 milliliter) = (100 parts per million)V2

• 13

  Solve for V1. ((1000 parts per million)(50 milliliter)) / 100 parts per million = V2, or 500 milliliter = V2. Therefore, 50 milliliters of 1000 parts per million need to be diluted to 500 milliliters with distilled water to equal a concentration of 100 parts per million.

Making 1000 PPM Stock for Dilutions

• 14

  Fill a 1000 milliliter volumetric flask or plastic container three-quarters full with distilled water. Using distilled water prevents contamination of the solution.

• 15

  Measure out 1 gram of potassium permanganate. Weighing on a scale provides the most accurate results.

• 16

  Add the 1 gram of potassium permanganate to the flask. Carefully make sure all the crystals make it into the container or flask---otherwise the concentration will be less than 1000 parts per million.

• 17

  Mix until all the crystals disappear.

• 18

  Fill the flask to 1000 milliliters. This solution equals 1000 parts per million of potassium permanganate.