Mischief Managed Lab
Name: _______________________________________________
Materials:
 8 containers:
o 2—containing 20 mL of red cabbage juice
o 1—containing 20 mL of lemon juice (acid)
o 1—containing 20 g of baking soda (base)
o 1—containing 20 mL of Substance A
o 1—containing 20 mL of Substance B
o 1—containing 20 mL of Substance C
o 1—containing 20 mL of Substance D
 4 cotton swabs
 spoon/stirring rod
 4 index cards
Substance A
Substance B
Substance C
Substance D
Procedure Part I—Invisible Ink:
1. Each student draw lines to split their notecard into four parts (see above).
2. Label spaces substance A, B, C, & D.
3. In each space paint a simple design using a cotton swab and the labeled substance. Use a
different swab for each substance.
4. Set the cards aside to dry (~30 minutes).
Hypotheses
Using your sight and smell (wafting only) make hypotheses about the pH of the four substances
(acidic or basic).
Substance A:
Substance B:
Substance C:
Substance D:
Procedure Part II—Reactive Liquids:
1. Add several drops of lemon juice to one cup of cabbage juice. Stir the solution.
Observations:
2. Add a spoonful of baking soda into the lemon/cabbage juice solution. Stir the solution.
Observations:
How can you tell if a substance is an acid or base using cabbage juice as an indicator?
Define:
Make sure to include how these terms relate to [H+] and [OH-].
Acid:
Base:
Indicator:
Procedure Part III—Reappearing Ink:
Make sure that the index card is dry.
Dip the Fifth cotton swab into the untouched cabbage juice. Swab the cabbage juice over the now
invisible designs and observe what happens.
Observations:
Substance A:
Substance B:
Substance C:
Substance D:
Conclusions:
Are the following substances acidic or basic? Use the pH probe to measure pH. Make sure to
clean between uses. Ask your teacher to identify the unknown substances.
Acidic or Basic?
pH
Identify the Substance.
Substance A
Substance B
Substance C
Substance D
Lemon Juice
_________________________________
Baking Soda
_________________________________
What is an advantage of using a pH meter over an indicator like cabbage juice?