Decanting a Liquid in Chemistry and an Experiment

Decanting is pouring off the clear part of the liquid, leaving behind the sediment.  When doing a lime-water test for carbon dioxide you need to decant the clear lime-water from the portion with the sediment.

This video shows how to decant a liquid.

Lime Water Experiment

The experiment we did was very simple.  You just need pickling lime, which you can get wherever canning supplies are sold, in Wal Mart or grocery stores, and distilled water.

  1. Pour enough distilled water into a jar or flask to fill it three quarters full.
  2. Add 2 Tablespoons pickling lime.
  3. Put a lid on the jar or a stopper on the flask.  Shake it up to dissolve and mix. Let it sit overnight.
  4. Decant the clear liquid into a beaker or another jar, leaving the sediment behind.
  5. Using a straw, blow into the clear liquid in the beaker.
  6. The lime-water in the beaker will turn cloudy in the presence of carbon dioxide.

lime-water-experiment

Additional Layers

  • This experiment could be done when studying the pulmonary system, photosynthesis and the carbon cycle, indicators in chemistry, or just as a general chemistry experiment for young kids.
  • Three chemistry vocabulary words for this experiment: decant, flask, beaker
  • The chemical name of pickling lime is calcium hydroxide.  The chemical formula is Ca(OH)2.  Find these elements on the periodic table.
  • Even though this experiment with pickling lime is not dangerous, Isaac was wearing safety goggles when he did it.  Whenever my kids use chemicals in science class, even baking soda and vinegar, they wear safety equipment.  This is because sometimes we use things like sodium hydroxide or hydrochloric acid and I want them in the habit and taking chemicals seriously.  Teach your kids to wear their safety gear for chemistry.  Goggles always, gloves when handling more serious chemicals, and aprons for the really dangerous stuff.

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