Date:
Name:
LAB: Properties of Acids and Bases
Purpose
In this activity you will look for several characteristics of both acids and bases to help derive definitions.
Then you will react an acid with a base and examine the product.
Materials
Test solutions of:
 hydrochloric acid
 sulphuric acid
 acetic acid
 sodium hydroxide
 barium hydroxide
 calcium hydroxide
25 mL graduated cylinder
glass stirring rod
red litmus paper
blue litmus paper
phenolphthalein solution
bromothymol blue (BTB)
evaporating dish
medicine dropper
bunsen burner
support stand
scoopula
(HCl)
(H2S04)
(CH3COOH)
(NaOH)
(Ba(OH)2)
(Ca(OH)2)
wooden splint
magnesium ribbon
2 test tubes
Procedure
PART A: ACIDS
1. Draw the following table in your lab report. Tabulate your results in the table.
Chemical
Action with:
Red Litmus
before
after
Blue Litmus
before
after
Phenolphthalein
before
after
Bromothymol
blue
before after
Magnesium powder
HCl
H2S04
CH3C00H
1.
2.
3.
4.
5.
6.
Wash your spot plate carefully and rinse it very thoroughly. Fill four (4) of the depressions with one
of the solutions. Return to your work station to work with the indicators.
Record the colour of each indicator BEFORE they are used.
Dip the Red Litmus paper in the first depression. Record the colour.
Dip the Blue Litmus paper in the 2nd depression. Record the colour.
Put 2 drops of Phenolphthalein in the 3rd depression. Record the colour. Be very careful to avoid
contact between the drop plate and the dropper.
Put 2 drops of Bromothymol Blue in the 4th depression. Record the colour.
7.
8.
9.
Obtain a test tube and fill it with 5 mL of the solution used in steps 1 to 6. Place the test tube in a test
tube rack.
Add a small amount of magnesium ribbon to the acid in the test tube standing in the test tube rack.
After 20 seconds, insert a blazing splint down into the test tube. Record your observations in the
chart.
Completely wash out the test tube and spot plate. Repeat steps 1 to 9 with each of the other two
acids. Complete your table.
PART B: BASES
1. Draw the following table in your lab report. Tabulate your results in the table.
Chemical
Action with:
Red Litmus
before
after
Blue Litmus
before
after
Phenolphthalein
before
after
Bromothymol
blue
before
after
Magnesium
powder
NaOH
Ba(OH)2
Ca(OH)2
1.
2.
3.
4.
5.
6.
7.
8.
9.
Wash your spot plate carefully and rinse it very thoroughly. Fill four (4) of the depressions with one
of the solutions. Return to your work station to work with the indicators.
Record the colour of each indicator BEFORE they are used.
Dip the Red Litmus paper in the first depression. Record the colour.
Dip the Blue Litmus paper in the 2nd depression. Record the colour.
Put 2 drops of Phenolphthalein in the 3rd depression. Record the colour. Be very careful to avoid
contact between the drop plate and the dropper.
Put 2 drops of Bromothymol Blue in the 4th depression. Record the colour.
Obtain a test tube and fill it with 5 mL of the solution used in steps 1 to 6. Place the test tube in a test
tube rack.
Add a small amount of magnesium powder to the base in the test tube standing in the test tube rack.
After 20 seconds, insert a blazing splint down into the test tube. Record your observations in the
chart.
Completely wash out the test tubes and spot plate. Repeat steps 1 to 8 with each of the other two
bases. Complete your table.
PART C: REACTING AND ACID WITH A BASE
1. Pour 5 mL of sodium hydroxide solution into
a clean evaporating dish. Use a stirring rod to
add two drops of phenolphthalein solution,
stir, and note any observable change. As you
stir the mixture, use a medicine dropper to
slowly add hydrochloric acid solution, drop by
drop, to the dish. When the pink colour just
disappears stop adding acid.
2. Set up the apparatus as shown in the figure
on the right and be sure you are wearing your
safety goggles. Evaporate the solution to dry- ness. Allow
the dish to cool.
3. Examine the solid substance that forms in the
evaporating dish.
DISCUSSION QUESTIONS
1. Look at the formulas for the acids you used. (See the table Part A.) What do they have in common?
2. Look at the formulas for the bases you used. (See the table Part B.) What do they have in common?
3. How do acids and bases differ in their effect on red and blue litmus paper?
4. How do acids and bases differ in their effect on phenolphthalein?
5. a) What happens when a metal such as magnesium is placed in an acid?
b) What happens when such a metal is placed in a base?
c) Name any gases produced in a) or b).
6. a) What happens when sodium hydrogen carbonate is placed in an acid?
b) What gas is produced?
7. a) What product was formed when hydrochloric acid reacts with sodium hydroxide?
b) The reaction between an acid and a base is called neutralization. Water and a salt are formed in
every neutralization reaction. Write a word and chemical equation for the neutralization reaction
that occurred in Part C.
8. a) List all properties common to acids and bases.
b) List all properties possessed only by acids.
c) List all properties possessed only by bases.
9. Suppose you are given five beakers, each containing an unknown liquid. One is distilled water, one
is a strong acid, one is a weak acid, one is a base and one is a salt solution. Describe how you would
find out which was which.