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
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
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?
Nylon 66 Yes
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.