Name_______________________________________
Date_______________
Acids vs. Bases
Background
Acids and bases are common substances that we come into contact with every day. There are acids in
the foods we eat and stomach acid is used to digest food. Bases are in soaps and shampoos and in
many cleaning products. What are acids and bases? What are the distinguishing properties of acids and
bases? In this laboratory investigation, you will explore tests that will help identify those distinguishing
properties of acids and bases.
Objectives
1. After completing this laboratory investigation, the student will be able to identify distinguishing
properties of an acid and a base.
2. After completing this laboratory investigation, given the properties of a substance, the student will
be able to determine whether a substance is an acid or a base.
Materials/Equipment
(per team)
24 well spot plate
Acetic acid (0.1 M, 5 mL)
Ammonium hydroxide (0.1 M, 5 mL)
Conductivity probe
Distilled water
Dropper pipet
Forceps
Hydrochloric acid (0.1 M, 5 mL)
Laptop or netbook computer
Magnesium ribbon (2.5 cm cut into 0.5 cm pieces)
Neutral litmus paper (5 strips)
Phenolphthalein solution (2 mL)
pH probe or pH test strips (5 strips)
Sodium hydroxide (0.1 M, 5 mL)
Stirring rod
Universal indicator solution (2 mL)
Vernier LabPro w/Logger Pro Software
Procedure
Perform the following tests for each acid and base in the data table as well as for the reference
substance, distilled water. All of the tests will be conducted by placing the solution in a well of a spot
plate. The tests can be done in any order but each test should be completed for all solutions before
proceeding to the next test. For each test, dispense 20 drops of each solution to be tested into a
separate well of the spot plate.
Name_______________________________________
Date_______________
1. Neutral litmus paper – Test each solution with a neutral litmus paper strip and record the color
formed.
2. pH value – Test each solution by using the Vernier Labpro and Logger Pro software with the pH
probe. Insert the probe into the solution and record the pH value.
3. Phenolphthalein – Test each solution by adding 3 drops of phenolphthalein indicator solution
and record the color formed.
4. Universal indicator – Test each solution by adding 3 drops of universal indicator solution and
record the color formed.
5. Conductivity – Test each solution by using the Vernier Labpro and Logger Pro software with the
conductivity probe. Insert the probe into the solution and record the conductivity value.
6. Reaction with magnesium – Test each solution by adding a piece of magnesium and record the
reaction speed if any. To ensure time for the magnesium to show signs of reaction, wait at least
5 minutes before recording reaction speed. Rate speeds from fastest to slowest.
Data Table
Property Tested
Distilled water
Acetic acid
Solution Tested
Hydrochloric
Sodium
acid
hydroxide
Ammonium
hydroxide
Neutral litmus
paper color
pH value
Phenolphthalein
color
Universal
indicator color
Conductivity in
mA
Reaction speed
with
magnesium
Data Analysis
Based on your test results:
1. From the neutral litmus test, what color is associated with an acid and what color is associated
with a base?
Name_______________________________________
Date_______________
2. From the pH value test, what pH values are associated with an acid and what pH values are
associated with a base?
3. From the phenolphthalein test, what color is associated with an acid and what color is
associated with a base?
4. From the universal indicator test, what colors are associated with an acid and what colors are
associated with a base?
5. From the conductivity test, what acid and what base could be considered strong?
6. From the reaction with magnesium test, what possible conclusion could be made about acids
and bases?
7. In a paragraph, describe the properties of an acid and a base resulting from your investigation.
8. Based on the properties of acids and bases, devise two methods to achieve the same test results
as you obtained for distilled water by combining an acid and a base.