I am trying to demonstrate color change in the liquid as it passes through a channel to demonstrate blood getting purified after passing through certain organs of the body.

I want the initial color of the liquid to be blue in color and as it passes and comes out of a small pipe, it should change into red color and again after going through a small pipe, I want it to change back into blue color.

In short, blue to red to blue.

I have tried to search things online and I found the following. There is a reaction which involves sodium hydroxide and sucrose. Under stirring upon addition of $\ce{KMnO4}$ the color change happens. But I am not quite sure if I will be able to handle stirring.

So, I am looking for something simpler than that. I am really not that sure if such a reaction exists.

  • 3
    $\begingroup$ Would passing through an ion exchange column be ok? $\ce{H^{+}}$ solution exchanged to $\ce{Na^{+}}$ solution in column 1, then exchange $\ce{Na^{+}}$ for $\ce{H^{+}}$ in column 2. So you need an indicator that is blue in acid and red in neutral solution. The ion exchange columns would work for a while. Then you'd have to take the system apart and "reload" columns using a flush with HCl acid and NaCl solutions to reload the columns again. $\endgroup$
    – MaxW
    Nov 4, 2015 at 6:55
  • 3
    $\begingroup$ Instead of coloring and recoloring the liquid it is probably easier to color the channel the liquid flows in. $\endgroup$
    – aventurin
    May 9, 2018 at 17:15


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