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Contributed by: New York State Education Department (NYSED)
Task: At this station, you will experiment to determine
which of three solutions is acidic and which is basic.
Materials:
- Solution filled disposable pipettes labeled A, B, and C
- Disposable pipettes with phenolphthalein
- Reaction transparency or plate
- Blue litmus paper
- Red litmus paper
- Red litmus paper
- Reaction transparency or plate
- Waste cup
- Paper towels
- Safety goggles
- Cassette case
- Water for cleaning
Background:
Phenolphthalein turns pink in a basic solution.
Blue litmus paper turns red (pink) when dipped
in an acidic solution.
Red litmus paper turns blue (purple) when dipped
in a basic solution. |
Directions:
- Put your safety goggles on. Do not taste or touch
any solution. Clean up all spills immediately.
- Place one drop of each solution, A, B, and C, on the circle
with the same letter in each of the three rows.
- Dip the end of a different piece of blue litmus paper into each
of the three solutions in the top row and lay them on the
plate.
- Immediately record the COLOR of the litmus paper on the
data table.
- Repeat steps 3 - 4 using the red litmus paper in the the
middle row and lay them on the table.
Table 1: COLOR results of litmus paper
| Indicator |
Solution A |
Solution B |
Solution C |
| Blue Litmus |
|
|
|
| Red Litmus |
|
|
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- Add one drop of phenolphthalein to each of the three solutions
in the bottom row.
- Record the COLOR of the phenolphthalein on the data table
below.
Table 2: COLOR results of phenolphthalein
| Indicator |
Solution A |
Solution B |
Solution C |
| Phenolphthalein |
|
|
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- Wash the plate or reaction transparency with water and dry with
a paper towel. Throw away any garbage into the waste cup.
- Using the data you have collected and the background information,
which solution is acidic?
_______________________________
In the space below, explain the reason for your answer. Refer
to Tables 1 and 2.
______________________________________________________________
______________________________________________________________
______________________________________________________________
- Using the data you have collected and the background information,
which solution is basic? _______________________________
In the space below, explain the reason for your answer. Refer
to Tables 1 and 2.
______________________________________________________________
______________________________________________________________
______________________________________________________________
NYS Alternative Assessment in Science Project
Copyright, April 1996
The State University of New York
The State Education Department
Albany, New York 12234
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