If you like us, please share us on social media, tell your friends, tell your professor or consider building or adopting a Wikitext for your course.

ChemWiki: The Dynamic Chemistry Hypertext > Under Construction > Demonstrations > Additional Demos > The Red-White-and-Blue Demonstration

The Red-White-and-Blue Demonstration


Chemical Concepts Demonstrated

  • Kinetics
  • Multi-step reactions


Three solutions are combined in alphabetical order.
  • Solution A: Na2SO3 * H2O dissolved in water mixed with 2,4,2',4',4"-pentamethoxytriphenyl methanol dissolved in acetone.
  • Solution B: Cd(NO3)2 * H2O and HCl added to water, shaken, and diluted.
  • Solution C: NaIO4 dissolved in water.


Solutions A and B produce a red solution.  Adding solution C after this turns the solution milky white, then blue after a time.

Explanations (including important chemical equations)

The hydrochloric acid in solution B turns the 2,4,2',4',4"-pentamethoxytriphenyl methanol (an indicator) red.  The addition of solution C causes the pH to increase due to the formation of OHions in the IO4- oxidation of S2O32-.

2 S2O32- (aq) + IO4- (aq) + H2O (l) --> S4O62- (aq) + IO3- (aq) + 2 OH(aq)

When the indicator turns colorless again, the milky-white suspension of Cd(IO4)2+ becomes apparent.  The further increase in pH triggers another indicator (thymolphthalein), turning the solution blue.



You must to post a comment.
Last modified
10:31, 2 Oct 2013



(not set)
(not set)

Creative Commons License Unless otherwise noted, content in the UC Davis ChemWiki is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. Permissions beyond the scope of this license may be available at copyright@ucdavis.edu. Questions and concerns can be directed toward Prof. Delmar Larsen (dlarsen@ucdavis.edu), Founder and Director. Terms of Use