Science Buddies: "Ask an Expert"

What questions or problems will I investigate with making pH paper with red cabbage?

Hi aprice65,

Welcome to the forum.

From your question it seems that you may you may be working out your project question. As your project involves making pH paper which can then be used for measurements in many kinds of experiments, I would say that the questions you might investigate fall into two areas. One question is “how does pH paper work?” and the other is “how can pH paper be used in experiments?”.

Some very useful information on making pH paper is provided in the project idea section at this url:

https://www.sciencebuddies.org/science- ... background

If you have more questions after reviewing this information please ask again.

I hope this helps. Good luck with your project!

A. Norman

Thank you Norman40,

This is my first major science fair project and I am a little nervous. I just have to understand what is project test is, which I understand. I am a bit confused/well unsure as to what my independent/dependent/controlled variable is. So, just so to verify for my pH paper project;

Independent - pH paper?
dependent - result of the different solutions on the pH paper?
controlled - same exact solutions on different pH paper.

Thanks in advance

Hi aprice65,

You are very welcome. I hope that your first major science project is a lot of fun!

In the "Science Fair Project Guide" section of this website is a great description of variable types. Reviewing this information may be useful.

For an experiment where the pH is measured for different solutions, the pH is the dependent variable. The solutions are the independent variable. You could have many controlled variables, one is the pH paper used for the measurements.

I hope this is helpful. Please let us know if you have more questions.

A. Norman

Independent Variable = something you are changing.
controlled variable = all the things you are NOT changing when you change the independent variable
Dependent Variable = the thing that you predict will change as a result of your adjustment of the independent variable



In your question that you are trying to answer with your experiment you can think of it as:

"I predict that when I change <independent variable> without changing <controlled variables> that <dependent variable> will change in <specific way>e"

You then try it and see if it happens as you predict, and try to explain anything unexpected that occurs.

An example would be....

"If I mix different types of fruit juice (independent) and into a glass of 2% milk (controlled) in equal quantities, 1 cup each (controlled) the taste of the milk in my mouth (dependent) will seem different "

(a better question would be to try to predict which would taste bad vs which would taste good, based on what you know about the properties of the different juice types and how they interact with milk)

What would my hypothesis be when making my own ph paper? So the factors that would be changed in this experiment, would be the paper color from each solution?

Hi aprice65,

You are doing this Science Buddies project, right?

https://www.sciencebuddies.org/science- ... p041.shtml

If you are making your own pH paper, then the question you are trying to answer is "Can I make home-made pH paper that gives reasonable results?" Your hypothesis would be something like, "If I make red cabbage pH paper, then I will be able to reasonably measure the pH of (list some of the items the procedure suggests testing)." You could then test the pH of those solutions (e.g., lemon juice, milk, water, baking soda solution) and see whether the colors of your homemade pH strips are consistent with the pH of the solutions (listed in Table 1 of the Background Information tab of the Project Idea).