Testing Cabbage Juice as a PH Indicator
Question: How does the acidity of a liquid affect the color of cabbage juice when combining them together?
Which of the different liquids are the most acidic?
Name: Silvana A and Novah K
School: Loma Ridge Elementary
Teacher: Mrs. Ung
Abstract
We are trying to determine the effects of the acidity of a liquid on PH indicators such as cabbage juice.
We predicted that if we add a specific liquid to cabbage juice, the liquid will change colors depending on the acidity of the liquid. What we did to test this is that we added a measured quantity of specific drinks or liquids to cups, then add a specific amount of cabbage juice to each liquid to see what color it changes into. Our data showed that some liquids changed colors more than others. Not knowing the exact PH of the liquids, our results suggest that by some liquids changing more than others, cabbage juice is a good PH indicator. Future testing should focus on evaluating how much the original color of the liquid affects the results of the tests, for example, root beer is brown, but would that affect the result to not change as much like Sprite or water?
Research
Cabbage juice has a pigment called anthocyanin that changes color at different PH levels (Agee, S. 2022), which is what makes cabbage juice a great PH indicator. If the substance turns red or pink, when adding the cabbage juice, it means its acidic. If it turns green or blue, sometimes even yellow, it leans more to the basic side (Buffalo Museum of Science).
Acidic Liquids | Cabbage juice |
Changes response of color E | C Has a Anthocyanin pigment |
More acidic C | E More red or pink in result |
Less acidic C | E More blue or green result |
Cause and effect! (C= cause, E= effect)
Hypothesis
If we add specific type of liquid to cabbage juice, then the cabbage juice will change colors, because acidic liquids will be more pink or red compared to more basic or neutral liquids.
We think that lemon soda, lemon juice, lime juice, vinegar, pink drink, orange gatorade, kool aid, root beer, water, and chocolate milk are the most acidic to the least acidic.
Materials
Materials (for each sample)
* cabbage juice (15 ml a cup to add to each drink)
* 20 ml vinegar
* 20 ml water
* 20 ml root beer
* 20 ml chocolate milk
* 20 ml kool aid
* 20 ml lemon soda
* 20 ml lemon juice
*20 ml lime juice
* 20 ml orange gatorade
*20 ml pink drink
* 10 glass cups for the drinks (For the tests, we used 4 for each liquid)
* jar for the cabbage juice
*measuring cups
Procedures
Results - Data/Observations
Results - Data/Observations (cont’d)
Conclusion/Results Discussion
Based on the data collected, we strongly believe that cabbage juice is a good PH indicator because on the fact that different substances of the same original color changed colors at different rates after addition of cabbage juice. For example, we experimented with water, vinegar, and lemon soda, which are all transparent, however the vinegar and the lemon soda changed color a lot more than the water did. This supports our hypothesis and the claim that cabbage juice is a good indicator of PH. Nevertheless, our results also show a high percentage error (difference between our prediction and our actual results) for rootbeer, showing 300% error. We suspect that it’s because rootbeer has a darker color, which might affect the reaction between root beer and cabbage juice. In addition, although we predicted low change for chocolate milk, our actual results for chocolate milk also support the idea that darker substances affect the ability of cabbage juice to be an indicator for PH by affecting the color it will turn into.
Application/Future Research
Our results can be applied to daily life, for example, if something is acidic, and you can’t eat anything acidic for a specific reason, you can use cabbage juice as a PH indicator to see if the substance is acidic, basic, or neutral. Additionally, we think chefs would be interested in knowing the results of our project because it can help them determine how the ingredients react to each other when they are using cabbage juice in their recipes.
To take our results to the next level, we would like to do more research and additional tests to see if the original color of a substance affects the results, for example, root beer is brown and dark, compared to Sprite and water which are clear. Also, we would like to investigate other substances to determine if these substances could also work as good pH indicators.
A new idea we would like to analyze is how other ingredients, such as sugar, salt, and baking soda can interact with cabbage juice to see if they impact on the pH of the substances. We could analyze this by adding these ingredients to water and other transparent liquids, and then test with cabbage juice for a direct comparison between them and the impact they have on the acidity of liquids.
References Cited
ACS Chemistry for Life. (n. d) Red Cabbage Indicator. Washington DC. Retrieved from URL https://www.acs.org/education/activities/red-cabbage-indicator.html
Agee, S. (2022) Cabbage Chemistry. USA. Retrieved from URL
Buffalo Museum of Science. (n. d) Cabbage Chemistry. Buffalo, NY. Retrieved from URL
https://www.sciencebuff.org/scienceactivity/cabbage-chemistry/