MINILAB 14.1 What do acids do?

Most acids tend to be reactive substances. Test the reactivities of three acids with several common substances, and develop an operational definition for acidic solutions. Measure the pH by using universal indicator and a pH meter.

PURPOSE: TO TEST THE REACTIVITIES OF THREE ACIDS AND TO DEVELOP AN OPERATIONAL DEFINITION FOR ACIDIC SOLUTIONS.

HYPOTHESIS:

 

 

MATERIALS: 6M sulfuric acid, 6M acetic acid, of 6M hydrochloric acid, microtip pipet, (3)12-well microplate, litmus paper, bromothymol blue indicator solution, litmus indicator solution, marble chips (calcium carbonate), pieces of zinc, aluminum, egg white, UNIVERSAL INDICATOR, pH METER, apron and goggles

PROCEDURE:

1. Wear an apron and goggles.

2. Add 10 drops of 6M hydrochloric acid, HCl, to wells 1-6 of a clean, 12-well microplate. In the same manner, add 10 drops of 6M sulfuric acid, H2SO4, to a second microplate wells 1-6 and 10 drops of 6M acetic acid, HC2H3O2, to a third microplate wells 1-6.

**Don’t forget to record your observations on the data table for each test.**

3. Dip blue litmus paper into the solutions in wells 1 for the three acids.

4. Add 2 drops of bromothymol blue indicator solution to wells 2 for the three acids. This indicator turns from blue to yellow as the solutions become more acidic.

5. In a similar manner, add marble chips (calcium carbonate) to wells 3 for the three acids; pieces of zinc to wells 4 for the three acids; pieces of aluminum to wells 5 for the three acids; and a small amount of egg white to wells 6 for the three acids.

6. Dip universal test paper into the solutions in wells 1 for the three acids. Determine the pH by matching with the color chart.  

7. Dip pH meter into the solutions in wells 1 for the three acids.

8. Add 2 drops of litmus indicator solution wells 1 for the three acids.

9. Dispose of all materials as directed by your teacher. Rinse the microplates with tap water, then distilled water.

 OBSERVATIONS

OTHER REACTANT

6 M HCl

6 M H2SO4

6 M HC2H3O2

LITMUS

 paper

 

 

 

BROMOTHYMOL BLUE

 

 

 

MARBLE

CHIPS

 

 

 

ZINC

 

 

 

 

ALUMINUM

 

 

 

 

EGG

WHITE

 

 

 

UNIVERSAL INDICATOR

 

 

 

pH

METER

 

 

 

LITMUS

solution

 

 

 

 

ANALYSIS

1. Summarize the reactions of the three acids with the substances you tested. This summary constitutes an operational definition of an acid.

 

 

2. Which acid, although it had the same molar concentration as the other acids, reacted less noticeably? Explain this behavior.