Science Buddies: "Ask an Expert"

I am working on my eighth grade science project. I am comparing red cabbage solution to litmus paper. Part of the assignment is to interview an expert. Would you please consider answering the following questions for my "online" interview?

What are some factors that will cause the red cabbage solution to read a different pH than the litmus paper?


Why does the red cabbage solution change color when mixed with acids and bases?


What other plants can be used as pH indicators?


How was red cabbage discovered to be a pH indicator?


Does the color/shade of the red cabbage affect the pH level of the solution?


Thank you so much! I appreciate you taking the time to assist me with this part of my science project.

Hi,

I just wanted to let you know we are looking for a chemistry expert to answer your interview questions. We'll have you answers pretty soon.

Tonya

Red cabbage contains a pigment molecule called flavin (an anthocyanin). This water-soluble pigment is also found in apple skin, plums, poppies, cornflowers, and grapes. Very acidic solutions will turn anthocyanin a red color. Neutral solutions result in a purplish color. Basic solutions appear in greenish-yellow. Therefore, it is possible to determine the pH of a solution based on the color it turns the anthocyanin pigments in red cabbage juice.

The color of the juice changes in response to changes in its hydrogen ion concentration. pH is the -log[H+]. Acids will donate hydrogen ions in an aqueous solution and have a low pH (pH < 7). Bases accept hydrogen ions and have a high pH (pH > 7).

Would it be possible to have your name and educational degree/title? I need to incorporate this into my report.

Sorry, but we're not able to release this information. I can tell you that this is where I got my information: http://chemistry.about.com/od/acidsbase ... icator.htm

Okay, that will work. Thank you!

MeganRose - As you work on your project, I wanted to add that this Science Buddies project on using cabbage as an indicator might have additional information that would be helpful for you in terms of the background and introductory material. Some of the answers to your questions are included here as well:

Cabbage Chemistry
https://www.sciencebuddies.org/science- ... p013.shtml

Good luck with the project!

Amy
Science Buddies