I recently saw a video on YouTube in which water, when mixed with a solution (I believe iodine was involved,) changed color based on its acidity. I am attempting to replicate this experiment, but cannot concoct the solution. Any help would be much appreciated.

EDIT: To clarify, if I had water with a ph of 10 it would turn red, but if the water had a ph of 4 it would turn green.

EDIT 2: I found the video in question http://youtu.be/_yi83kOB8ug

  • $\begingroup$ Can you give us more details on the experiment? A link to the youtube video would be helpful for a start. $\endgroup$ – bon Nov 6 '15 at 17:48
  • $\begingroup$ Say I have highly acidic water. When I combine it with the solution, the water should turn red. If however, it had low acidity, it would turn blue. $\endgroup$ – Brandon Bradley Nov 6 '15 at 18:08

I'm assuming that you're doing this at home. A popular (and SAFE!!) experiment at home is to use red cabbage, vinegar, and baking soda.

The indicator comes from the cabbage.

Vinegar turns the solution acidic.

Baking soda turns the solution more alkaline.

  • $\begingroup$ What would the operating procedure be? How would you use this to, as an example, make highly acidic water a certain color? $\endgroup$ – Brandon Bradley Nov 6 '15 at 18:04
  • $\begingroup$ If you are trying to reproduce the exact experiment that you saw on youtube, then I'll need a link to the video. // In general an "indicator" is used to signal pH changes (or the pH) in a solution. The indicator undergoes a acid-base transition too, but is low concentration and deemed a "spectator" rather than a participant in the reaction. // There are a zillion pH indicators that can be purchased. en.wikipedia.org/wiki/PH_indicator I didn't see one like you described, but indicators are sometimes used in combination too. $\endgroup$ – MaxW Nov 6 '15 at 18:15
  • $\begingroup$ Alright, I added the link. Thanks for the information regarding the indicator. Let me know what you think. $\endgroup$ – Brandon Bradley Nov 6 '15 at 18:26
  • $\begingroup$ Yuck. I think they are trying to sell their water purifier. The music is god-awful. I saw a couple of pH changes. I'm too lazy to watch the whole thing and track all the changes. // Any bottled water or tap water would be safe to drink. Fancy "sparking water" has CO2 and will be acidic. // It is a mixed indicator for sure. I'd guess that a store which sells pool supplies would have some sort of such pH testing kit. Either paper strips or dropper solution. $\endgroup$ – MaxW Nov 6 '15 at 18:38
  • $\begingroup$ Agreed. In any case, it seems as though the best way to run an accurate version of this would be to use an indicator like you mentioned before. Thank you for helping me understand. $\endgroup$ – Brandon Bradley Nov 6 '15 at 18:42

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