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									    Prelab Quiz Answers
    Reproduce the diagram of the well plate shown and label it as you plan to use it. Interpretation of the experiment is
1   simplified if the known solutions are arranged in the order found in Data Table 4.1




                                                            Boric Acid








                     Carbon Dioxide

                                          Distilled Water

                                                                                              Unknown C

                                                                                                               Unknown D
                                                            Unknown A

                                                                             Unknown B
                     in Water

    A correlation between pH of a solution and its color in the presence of Yamada's Universal indicator is given in the
2   procedure section of the lab. What color would you expect a strongly basic solution?

          Dark Blue or Violet
3   What is the purpose in Part II of the experiment, in which the known solutions are spotted on DY4 paper?

          To determine if DY4 is an acid or base indicator
4   Why, after dying the multi-fiber strip, is it rinsed first with distilled water and then with tap water?

          To determine which fabrics are dyed by the DY4 paper (which materials the
          indicator will bind to) and then to determine which fabrics, once bound or dyed,
          are pH sensitive
                                 Lab 5 Answers

                     Yamada                  Acid/Base/                                           Color on DY4
                                  Litmus                      pH                     Solution
                      Color                   Neutral                                                Paper
0.1M Al2SO4            Red         Pink       Acid            2              0.1M Al2SO4            Clear
2M NH4Cl             Orange       Violet      Acid            4              2M NH4Cl               Clear
0.3M Boric Acid       Yellow      Violet      Acid            6              0.3M Boric Acid        Clear
1M NH4Ac              Green       Violet     Neutral         7-8             1M NH4Ac              Orange
0.2M Na3PO4            Blue        Blue       Base            9              0.2M Na3PO4            Red
0.2M Na2CO3           Violet       Blue       Base          10-11            0.2M Na2CO3          Dark Red
Dry Ice (CO2)          Red         Pink       Acid           2-3             pH at which DY4
Distilled Water                                                              changes
                      Green       Violet     Neutral          7                                       7-8
Unknown A              Red         Pink       Acid           2-3
Unknown B             Violet       Blue       Base           10              Fiber                Color Fast     pH Sensitive
Unknown C             Green       Violet      Base           7-8             Acetate
Unknown D             Yellow      Violet      Acid           5-6             Self-Extinguishing
                          Questions:                                         Arnel
                                                                             Bleached Cotton          Yes            Yes
1   What universal indicator colors are associated with acid solutions?      Creslan 61
    Red, Orange, Yellow                                                      Dacron 54
2   What universal indicator colors are associated with base solutions?
                                                                             Dacron 64
                                                                             Nylon 66                 Yes
                                                                             Orlon 75
    Dark Green, Blue, Violet
                                                                             Spun Silk                Yes
3   What universal indicator colors are associated with neutral solutions?
                                                                             Rayon                    Yes            Yes
    Green or Light Green                                                     Wool                     Yes
4   Recall that the philosophical origins of acids and bases may be traced to the warring opposites philosophy of
    Empedocles; such a philosophy tends to emphasize extremes (good vs. evil, black vs white). Litmust is a two color
    indicator whereas universal indicator is a multicolor acid base indicator. This multicolor behavior of the universal
    indicator represents a chemical reality and not a chemical philosophy. Do the results suggest that there are only two
    extreme measurements: acid or base?
    No, various different levels of pH indicate various strengths of acid and base. In
    addition, there is also neutral, which is neither acid nor base.

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