Indicator
Measuring the pH Level in Household Substances
Using Red Cabbage Juice as the pH
Jocelyne Cortes
Mrs. La Salle
Chemistry/Period 3
5/28/2013
PURPOSE
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To experiment and gain knowledge about calculating pH values
in different substances.
MATERIALS
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(1) Knife
Sliced Red Cabbage Leaves
(1) 1-cup Measure
(1) Pot of Hot Water
(2) Jars
(1) Clean White Cloth
(1) Teaspoon
(1) Roll of Tape
(3) Sheets of Blank White Paper
(1) Black Marker
(1) Ruler
(1) Spoon
(10) Clear Plastic Cups
White Vinegar
Baking Soda
Household Ammonia (Windex)
Other Household Items
-Salt, Milk, Dish Detergent, Mouthwash,
Toothpaste, Shampoo, All-Purpose Household Cleaner
PROCEDURES
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Step 1: Make sure all the red cabbage leaves are chopped up. Measure about 2 cups of the chopped up
red cabbage and pour it all into the first available jar. Next, pour 2 cups of hot water into the jar as well.
Next, grab the spoon and stir/crush the red cabbage juice in the hot water until a solid dark blue color has
established. With the white piece of cloth, place it over the second jar and grab the first jar and carefully
pour the substances from the first jar into the second. This is basically straining the extract away from the
liquid which is the pH indicator liquid.
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Step 3: Next, make a pH scale. Tape the three pieces of paper together (the hotdog way). Draw a straight
line horizontally through the middle all three pieces of paper. Now measure 5 cm from left to right and
for every 5 cm draw a line, that line will represent a pH value. The pH scale should be 1-14.
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Step 4: Set up all 10 plastic cups and label them with the household substance whose pH will be
evaluated. (Salt, Vinegar, Baking Soda, Toothpaste, etc.) Next, for each empty cup, place about 1 cm worth
of the cabbage pH indicator. Now, depending on what the cup is labeled, drop a small amount of each
labeled substance into the cup, mix, and observe the change in color that occurs. Repeat until all
substances have been tested.
Vinegar
Baking
Soda
Ammonia
…MORE HOUSEHOLD ITEMS TESTED
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Step 5: Based on the result of color, attempt to correctly align
them on the pH scale from base to acid (1-14).
RESULTS
•DISHWASHER DETERGENT: 1
•TOOTHPASTE: 2
•VINEGAR: 3
•MILK: 4
•MOUTHWASH:5
•ALL PURPOSE HOUSEHOLD CLEANER: 5
•SHAMPOO: 6
•CABBAGE JUICE (INDICATOR): 7
•SALT: 7
•BAKING SODA: 9
•WINDEX: 11
ANALYZE AND CONCLUDE QUESTIONS (PG 604)
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The color of the indicator in
 Acidic Substances: Lighter colors. For instance, the Dishwasher Detergent was
bright yellow (estimated pH of 1) and the Vinegar turned to be a light hot pink
(estimated pH of 3).
 Neutral Substances: The natural color of cabbage which was a solid blue. The
salt also turned our to be that exact shade of deep blue. They’re pH was
estimated to be a neutral 7.
 Basic Substances: These tended to be on the darker side, for example the
ammonia with an estimated pH of 11 was a dark green. Baking soda can be
guessed to have a pH of 9 and its color was a very dark bluish green.
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The chemical changes responsible for the color change was in the red
cabbage juice indicator because its hydrogen ion concentration
changed when a test substance was added to it. Acids produce
hydrogen ions in aqueous solution. Bases contain hydroxide ions. A
substance is neutral because of equal numbers of hydrogen and
hydroxide ions
 Results for materials tested:
•DISHWASHER DETERGENT: ACID
•TOOTHPASTE: ACID
•VINEGAR: ACID
•MILK: ACID
•MOUTHWASH: ACID
•ALL PURPOSE HOUSEHOLD CLEANER: ACID
•SHAMPOO: ACID
•CABBAGE JUICE (INDICATOR): NEUTRAL
•SALT: NEUTRAL
•BAKING SODA: BASE
•WINDEX: BASE
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The group that contains items used for cleaning or personal
hygiene are the acids. For example, toothpaste, mouthwash, and
shampoo were all found to be acids.
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Conclusion
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Based on my results, I can confidently say I mastered the purpose of
this lab. I was able to understand not only the differences between
acids and bases but also comprehend how hydrogen and hydroxide
concentrations are the what affect whether a substance will be a base
or acid. The aspect that makes me question my certainty of this lab is
how on the Dishwasher Detergent, I might have placed it in the wrong
section. I now believe that it should have had a pH of around 4, but I
feel as though my error occurred when the color of pH came for milk.
It was such a peculiar color that it just through off my entire placing.
Overall, the rest of my results comply with the purpose in the sense
that they correctly describe the expected pH of that substance.