-
Aim: The aim of this experiment was to test various household chemicals to determine if they are acidic, basic, or neutral using different pH indicators.
-
Equipment:
- Blue litmus paper
- Red litmus paper
- Universal indicator solution
- Household chemical samples (Toilet cleaner, Dish liquid, Floor cleaner, 7-up soda, Spray wipe, Fabric softener, Vinegar)
- Spot plate or small containers
- Droppers
-
Method:
- Place a small amount of each household chemical into separate wells on a spot plate.
- Dip a piece of blue litmus paper into the first chemical and record any color change.
- Dip a piece of red litmus paper into the same chemical and record any color change.
- Add a few drops of Universal indicator to the chemical and record the final color.
- Repeat steps 2 to 4 for all remaining household chemicals.
- Match the Universal indicator colors to a pH color chart to determine if they are acids, bases, or neutral
-
Discussion:
-
What colour did each indicator change in an acid vs. a base? In an acid, both types of litmus paper turned red, and the Universal indicator turned red or orange. In a base, both types of litmus paper turned blue.
-
Why did indicators change colour? Indicators contain chemical compounds that react and change their chemical structure—and therefore their color—when they come into contact with hydrogen ions (acids) or hydroxide ions (bases).
-
Why did different household chemicals change different colours? Different household chemicals have different levels of strength (pH levels). Stronger acids turned the indicator bright red, while weaker acids turned it orange.
-
How did you know if these chemicals were acidic or basic? We knew they were acidic if they turned the litmus paper red, and basic if they turned the litmus paper blue.
Why might Universal indicator be more useful than Litmus paper? Litmus paper only tells you if a substance is an acid or a base (a simple yes/no answer). Universal indicator is much more useful because it shows a rainbow of colors, telling you exactly how strong or weak the acid or base is.
-
-
Conclusion:
-
did all your experiments work – if they didn’t, why? Most of the experiments worked well, but there were some confusing results. For example, the floor cleaner and fabric softener turned the litmus paper blue (indicating a base) or red (indicating an acid), but the Universal indicator turned orange. This conflict might be because the original colors of the chemicals messed up the final indicator color.
-
What could you do to improve your science next time? Next time, we could use clear or colorless household chemicals so their original colors do not interfere with the color of the indicators.
-
How could you make your results more reliable? (think about human error). To make the results more reliable and reduce human error, we could repeat the experiment three times to see if we get the exact same colors. We could also use a digital pH probe to get an exact digital reading instead of guessing the color by eye.
-