I am looking for advice on how to do a color change demo for a Cub Scout ceremony. I would like to have a liquid go from clear to orange to yellow to blue. I was considering using thymol blue since it seems to have the right colors at various pH levels. Can anyone lend some tips?
Thank you in advance.
color change demo orange to yellow to blue
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scoutleader824
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kaylimasuda
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Re: color change demo orange to yellow to blue
Thymol blue is a great choice. It transitions from red to yellow at pH 1.2–2.8 and from yellow to blue at pH 8.0–9.6.
If you use thymol blue, the process would be the following: (The below are very informal "procedures." I just wanted to get the ideas across.)
1. Make a very acidic solution (below 1.2pH). This acidic solution is clear without the pH indicator, which is thymol blue. (Note: Any solution would be clear without the indicator. However, it makes sense to have an acidic solution prepared so that the color change is from clear to your desired red.)
2. Add the indicator. The solution becomes a red/orange color.
3. Add a base until the solution becomes neutral (above 2.8 pH to below 8.0 pH). The solution would become a light-orange/dark-yellow color.
4. Continue to add the base until the solution becomes very basic (above 9.6 pH). This would be seen as a blue color.
There are many acids and base to choose from, but I often choose with vinegar and bleach since they're relatively safe and easy to find at your local store.
I hope this helps! Ask any questions if you have any!
-Kayli Masuda
If you use thymol blue, the process would be the following: (The below are very informal "procedures." I just wanted to get the ideas across.)
1. Make a very acidic solution (below 1.2pH). This acidic solution is clear without the pH indicator, which is thymol blue. (Note: Any solution would be clear without the indicator. However, it makes sense to have an acidic solution prepared so that the color change is from clear to your desired red.)
2. Add the indicator. The solution becomes a red/orange color.
3. Add a base until the solution becomes neutral (above 2.8 pH to below 8.0 pH). The solution would become a light-orange/dark-yellow color.
4. Continue to add the base until the solution becomes very basic (above 9.6 pH). This would be seen as a blue color.
There are many acids and base to choose from, but I often choose with vinegar and bleach since they're relatively safe and easy to find at your local store.
I hope this helps! Ask any questions if you have any!
-Kayli Masuda