Summer Research Program/Partners in Science Program
Mr. Robert Nociti
George Washington H.S., Manhattan
1998
How can we make mini-molar concentrations of HCl?
Materials: Stock solution of 1 Molar HCl
Mini pipettes and tips
Distilled water
Glass vials
Paper pH
Eyedroppers
Glass Plate [Teaching Standard D- Make accessible science tools]
Procedure:
Calculate amounts of 1M HCl and distilled water needed to produce
1ml of .1M HCl
1ml of .01M HCl
1ml of .0001M HCl
1ml of .00001M HCl
Using proper laboratory techniques make solutions.
Place 4 pieces of pH paper on a glass plate and test each solution on different papers using the eyedropper provided. (rinse eyedropper between each test) [9-12 Content Standard E- Understandings about science and technology]
Record colors produced and corresponding pH on chart provided. [Content Standard Unifying Concepts- Change, constancy, and measurement]
Questions:
What safety equipment did you use and why?
What do concentrated and dilute mean? [9-12 Content Standard B- Properties of matter]
Why must the eyedropper be rinsed between tests?
What happens to the pH of an acid solution as it is diluted by water?
Why do safety labels on chemicals often indicate flushing eyes and skin with water in case of accidental contact?
Concentration |
Vol HCI (1M) |
Vol H20 |
Color |
pH |
1 X 100 M |
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1 X 10-1 M |
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1 X 10-2 M |
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1 X 10-3 M |
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1 X 10-5 M |
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