Acid and Base Experiment- What is Ph for Kids
In this post, we will look at how to do an acid and base experiment to help kids understand what pH is and how it is measured.
What is pH, Acids and Bases (Explanation for Older Children)
The pH measures how acidic or basic (alkaline) a substance is. It ranges from 0 to 14, with 7 being neutral. Substances with a pH less than 7 are acidic, and those greater are alkaline. The lower the value on the pH scale, the stronger the acid. The higher the number on the pH scale, the stronger the base.
The pH measures the presence or absence of hydrogen ions. Acids and bases are created by the presence of charged ions (H+ or OH-) that help make up the chemical. Acids have hydrogen ions (H+) and bases have hydroxide ions (OH-). The greater the concentration of these ions, the more acidic or basic the substance.
When an acid and base come in contact with one another, a chemical reaction occurs. They neutralize one another by breaking apart and reforming into new substances. Each time this happens, water (H2O) and a salt is formed.
What you need – acid & base experiment
- Red Cabbage Juice or ingredients to make red cabbage juice (see instructions below)
- Purple cabbage leaves
- Blender or Cuisinart
- Fine strainer or coffee filter
- Small containers or ice cube tray (small transparent or white containers work best to be able to see the colours).
- Eye goggles or glasses recommended if children using stronger household products such as glass cleaner.
- Household substances to test such as:
- Lemon juice
- Baking soda
- Dish soap
- Glass Cleaner
- Tomato (juice)
- Hot sauce
- Laundry detergent
- Shaving foam
- Orange juice
How to make red cabbage juice
Place approximately 5 red cabbage leaves (you may need to rip them up) for every 1 cup of water into a blender. Blend until it turns into liquid. You can use the juice as it is, or you can pour it through a strainer or coffee filter.
Other substances that change colours depending on the pH include purple grape juice, turmeric and beetroot juice. You might notice that other fruits or vegetables such as radish, onion and even some flowers also change colours in the presence of acids and bases. Hydrangea flowers are pink when grown in alkaline soil and blue when grown in acid soil!
Testing pH on household items – What is Ph for Kids?
To prepare this experiment, choose several household products to test. If you are doing this with young children, it is best to choose ‘taste safe’ options from the list. *Please supervise this activity closely and use protective equipment if you use stronger household products with children.
Pour about 1 table spoon of each substance in to separate containers (less for small containers like an ice cube tray). Then allow children to pour or use a pipette to drop cabbage juice into each container to see what happens!
Questions to ask
- What colours can you make with the cabbage juice? Do they make all the colours of the rainbow?
- What do you notice when you put in the cabbage juice?
- What do you notice when you use beetroot, turmeric, grape juice or another indicator?
- What questions do you have about this?
- Is there anything else you would like to know? Can you design an experiment to answer one of the questions?
What they get from it
This is a fun way for children to begin to learn about pH and natural pH indicators. Doing this hands-on experiment will also allow them to observe, predict, record and discuss what they discover. Doing experiments like this will help children begin to develop scientific skills and scientific thinking. Further, research shows that people learn best (for long-term memory at least) through practical, hands-on experiences. (Ferri, et al., 2016; Hearns, Miller & Nelson, 2009; Hillman, 2011).
Cabbage juice (left) and then with different substances added to cabbage juice (right).
Take it further – Acid and Base Experiment
It can be great for children to create experiments to build on what they have done. You may want to ask questions to extend their learning such as: What questions do you have about these reactions? Is there anything else you would like to know? Can you design an experiment to answer one of the questions?
References -What is Ph for Kids
Ferri, B.H., Ferri, A.A., Majerich, D.M., Madden, A.G. (2016). Effects of In-Class Hands-On Laboratories in a Large Enrollment, Multiple Section Blended Linear Circuits Course. Advances in Engineering Education, 5 (3). https://files.eric.ed.gov/fulltext/EJ1121997.pdf
Hearns, M.K., Miller, B.K. and Nelson, D.L. (2009). Hands-On Learning versus Learning by Demonstration at Three Recall Points in University Students. OTJR: Occupation, Participation and Health, 30 (4), 169-171. https://journals.sagepub.com/doi/10.3928/15394492-20090825-01
Hillman, C.N. (2011). The effects of hands-on learning versus learning by demonstration on memory in community dwelling older adults (Doctoral dissertation, The University of Toledo). Retrieved from https://pdfs.semanticscholar.org/6231/d55fc1c730ec086f012677c54141f466e18e.pdf