Qualitative observations were made on five powders using three different chemical indicators (Liquids #1, #2 & #3). The chemical names of the powders and liquids were not known. Three of the five powders (A, B & C) were used as standards to identify two unknown powders (X₁& X₂). X₁ & X₂ were thought to contain only powders A, B or C, or mixtures of A, B and C.

METHODS AND MATERIALS:

1. Nine test tubes of two different types are needed to test powders A, B & C in this investigation. Six small (60 mm X 5 mm) glass tubes will be used to test all three powders with Liquids #1 and #2. The remaining three tubes should be Pyrex, or Kimax as they will be used to test the powders with liquid #3. The Liquid #3 tests require a boiling water bath for three to five minutes.

The small glass tubes are disposable, so they may be thrown away after the tests have been performed and read. The Pyrex/Kimax test tubes are reusable and will need to been washed out after using.

2. Each of the jars of powder (A, B & C) has a spatula attached to it by a rubber band. To avoid contaminating other samples, and getting false data, be sure to use ony the spatula on each bottle to remove the powder from that bottle. Be sure you replace the spatula on the same bottle after use.

Using the spatula, put approximately 3 mm. of powders A, B and C in three separate tubes.

a. Two small glass tubes of Powder A.

b. Two small glass tubes of Powder B.

c. Two small glass tubes of Powder C.

d. Three Pyrex/Kimax test tubes:

a. One containing powder A

b. One containing powder B

a. One containing powder C

3. Each of the powders in the small glass tubes will be tested with liquids #1 and #2.

a. Put three drops of liquid #1 in tubes A, B and C.

b. Put three drops of liquid #2 into tubes A, B and C.

Pay close attention to the reaction that you get with the liquids. These indicators produce instant results. Describe and record the results.

c. Put enough of liquid #3 into the Pyrex/Kimax test tubes containing Powders A, B and C to just cover the powder. Place these test tubes in the boiling water bath and wait 5 minutes. Remove the tubes with a test tube holder . Place them in your test tube rack. Describe and record the results.

4. IF THERE IS CONFIDENCE AT THIS POINT THAT POWDERS A, B AND C CAN BE IDENTIFIED WITH LIQUIDS #1, #2 AND #3, THEN USE THE SAME TESTS TO DETERMINE THE CONTENTS OF BOTTLES X₁ AND X₂. IF A DEGREE OF UNCERTAINTY EXISTS ABOUT THE TEST RESULTS ON A, B AND C, THEN REDO THE TESTS.

 

	Powder A	Powder B	Powder C	Powder X1	Powder X2
Liquid #1	-	-	+ Gas Release	-	-
Liquid #2	-	+ Black color	-	+ Black color	-
Liquid #3	+ Orange color	+ Green/Orange color	-	+ Green/Orange color	-

The powders X₁ and X₂ were as expected in one case, but not the other. The indicators #1, #2 and #3 were sufficient to identify substances A, B and C.

Reagent #1 reacted with C to produce a distinctive gas release. Powder B turned black when three drops of liquid #2 was added to the tube. The data shows some conflict with A and B using indicator #3. It appears that A and B share some chemical relationship as they have results that are similar. The blue liquid reacted with powder A after being in the water bath, and appears to have chelated the molecules of A producing a copper-colored (orange) substance. Powder B had a similar result, but a greenish (as in oxidized copper) residue was also present with an orange (copper-colored) portion of B. The fact that B turned black with liquid #2 will confirm its presence in a test, but the results of A and B with #3 was thought to be conflicting and could make the identification of X₁ and X₂ confusing.

X₁ had a positive response to liquid #2 in that it turned black when three drops of reagent were added. Liquid #3 produced a substance that appears to be relatively the same as standard B with reagent #3 after heating. All other tests on X₁ were negative. Testing X₂ with indicators #1, #2 and #3 produced none of the results seen in powders A, B and C. All of the tests on X₂ were negative.

Indicator #2 confirmed that substance X₁ contained standard B. Indicator #3 supports that B is present in X₁, and it alludes to A possibly being in what could be a mixture of other powders. Tests with A, B and liquid #3 were repeated with similar results. The evidence points at X₁ containing B, but does not rule out other substances being present in the jar containing X₁. With only three standards available to identify the chemical content of containers X₁ and X₂, the results of this investigation are seen as tentative and indicates that other testing should be done.

X₂ does not contain any of standards A, B or C. All tests here were negative. Again limited by only three standards the identification of X₂ remains to be determined. More testing is needed on X₂, with other different standards, if a positive identification is to be made.

 

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