Elephant's toothpaste

This week, I would like to talk about a common classroom demonstration—elephant’s toothpaste. The reaction behind this experiment is quite simple. It’s just about the spontaneous decomposition of hydrogen peroxide (H₂O₂) and the equation is showed below:

Here is the “recipe”:

1. 100 mL 30% hydrogen peroxide

2. 2.5 g KI

3. 20 mL surfactant

4. 3 mL fod coloring (or watercolor) in any color you like

    Put these things all together in a cylinder or something is long and has an upward opening than there will be a amazing show like this:

           So… it’s obvious why it gets its name “elephant’s toothpaste” ~~

           I want to talk about the role of each agent now. Hydrogen peroxide, is the main reagent while potassium iodide (KI) serves as catalyst (催化劑) and can be replaced by yeast or ferric cation (Fe³⁺). The present of catalyst makes the reaction much faster. Surfactant is used to retain the oxygen produce by decompose and makes bubbles. Finally, the coloring is optional because they are merely used to make the experiment colorful XD

    Enjoy yourself with this easily-conducted experiment!

*Attention

1. The decomposition reaction is exothermic and will make the container quiet hot!

2. 30% hydrogen peroxide is a strong oxidant which may cause serious result, please handle it with care!

Reference:

1. http://pubs.acs.org/doi/pdf/10.1021/acs.jchemed.5b00037

2. https://en.wikipedia.org/wiki/Elephant_toothpaste

NanoPutian

    NanoPutian is a class of organic compounds that were synthesized by James Tour et al. for educational purpose in 2003. The word “NanoPutian” consists of “nano” and “putian”. “Nano” is a prefix means 1*10^-9, like we usually say "nanometer", "nanogram", and “nanotechnology”. “Putian” originated from the word “lilliputian”, which means a very little world and refers to a fictional nation in Gulliver’s Travels called “Lilliput”.

    Let’s see some examples of NanoPutian and you will definitely have a deeper insight into them.

This is NanoKid:

    What's more, there are various characters that only differ from their heads, and here are some examples*:

  
  These are polymer and dimer of NanoPutian:

    Though the research of NanoPutian may seen meaningless, what Professor J. Tour was trying to do is to introduce more young scientist and the public to the microscopic nano-world. Also, he demonstrated to us that organic chemistry had already been well-developed and can synthesize almost any structure we want. 

    But for me, I think he was conveying that “scientist should study what they are interested in”. After all, the interest is the biggest motivation putting forward a scientist on the way of research. Someday, I hope I can become a chemist and devoted myself into studying what interested me, too!

    The article must end, but I wish you can be inspired and develop a long-lasting interest in chemistry as I do!

*The wave-like bond in the picture means bond without certain configuration.

#The original paper may help you with more details about NanoPutian, and here is the link: http://chemistry.mdma.ch/hiveboard/picproxie_docs/000466038-anthropomorphic.molecules.art.pdf

Chemical clock reaction

Hello everyone! I'm 劉俊廷 and I hope you can be impressed by the reaction I described this week!

   Chemical clock reaction, or oscillating reaction, is a type of reaction that the concentration of certain compounds fluctuating over time. Usually, this kind of reaction shows rapid changes in color, and that’s why it’s often used as a magic or demonstrated experiment. Not only is the reaction spectacular, but the studies of the mechanism behind the color change indeed provide us insights into chemical kinetics. What’s more, it even resulted in the emerge of two brand new field—non-equilibrium thermodynamics and non-linear dynamics.

    Examples of chemical clock are quiet rare. Beside the common iodine clock which perhaps everyone has conducted it in high school, there are also BZ reaction, Briggs-Rauscher reaction and Bray-Liebhafsky reaction.

   

   Here are some videos regarding them:

*iodine clock

*BZ reaction

*Briggs-Rauscher reaction

   The mechanism behind these reactions is really complex. To be short, there all exists two reaction pathway—one generates the reactant (or product), and the other depletes the reactant (or product). So that’s why we see the color, which implies the concentration of chemical compounds, changes periodically. To make this blog science popular, I don't want to talk too academic. But anyone who wants to learn more can just contact with me:)