Columbia University

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

       

1 X 10-1 M

       

1 X 10-2 M

       

1 X 10-3 M

       

1 X 10-5 M

       

 

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