Illustrated Guide to Home Chemistry Experiments

106 DIY Science: Illustrated Guide to Home Chemistry Experiments

dISoALp S : The aqueous waste can be flushed down

the drain with plenty of water. The few milligrams of solid

iodine can be flushed down the drain or disposed of with

solid household waste.

CUTIOA nS

Iodine is toxic and irritating, and stains skins and clothing.

Stains can be removed with a dilute solution of sodium

thiosulfate. Lighter fluid is flammable. Wear splash

goggles, gloves, and protective clothing.

1.f you have not already done so, put on your splash I

goggles, gloves, and protective clothing.

2. Fill a test tube about halfway with water.


3. Add about 1 mL (~20 drops) of Lugol’s solution to the
   test tube. Stopper the tube and agitate it until the
   contents are thoroughly mixed. Record anything unusual
   about the appearance of the aqueous solution on line A
   of Table 6-4.


4. Use the eyedropper to carefully add about 1 mL of lighter
   fluid to the test tube by allowing it to run down the inner
   surface of the test tube, as shown in Figure 6-5. (If you
   substitute another solvent for the lighter fluid, make
   sure that it forms a distinct layer on top of the aqueous
   solution of iodine. If it doesn’t, you’ll have to start again,
   using a solvent that does not mix with water.) Record
   the appearance of the organic solvent layer on line B of
   Table 6-4.


5. Stopper the test tube and agitate it vigorously for 15
   seconds. Record the appearance of the mixed layers
   immediately after you complete the agitation on line C
   of Table 6-4.


6. Place the test tube in the rack and allow it to settle
   for 30 seconds or so. Record the appearance of the
   aqueous and organic layers on lines D and E of Table 6-4.


7. After the two layers have separated completely, use
   the eyedropper to draw off the top (organic) layer as
   completely as possible. Transfer the organic layer to the
   watch glass and set it aside to allow the solvent
   to evaporate.


8. Add about 1 mL of lighter fluid to the aqueous solution.
   Stopper the tube, agitate it, and wait for the layers to
   separate. Record the appearance of the aqueous and
   organic layers on lines F and G of Table 6-4.

POCEDURER

oALIpToN ACTIvITIES

If you have time and the required materials, consider

performing these optional activities:

• Repeat the experiment, beginning with two test
  tubes, each of which contains 10 mL of water and
  1 mL of Lugol’s solution. Add 1 mL of lighter fluid to
  the first test tube and add 5 mL of lighter fluid to the
  second. Agitate the tubes. After settling, compare
  the appearances of the aqueous layers to determine
  whether using additional lighter fluid causes more of
  the iodine to be extracted from the aqueous layer.


• Repeat the experiment, substituting three or four
  different food colorings for the iodine (one color
  per tube).

FIGURE 6-5: The aqueous iodine solution (right) with an upper organic layer (left) before extraction

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