Editing Potassium Permanganate And Glycerin

{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Chemistry]]:
| Rate of Reaction, Redox Reactions
|-
| Grade Range:
| [[Elementary School]], [[Middle School]], [[High School]]
|-
| Format:
| [[Stage]]
|}

This demonstration produces smoke and fire, so be sure to check with the school or event coordinator if smoke and fire are OK before bringing this demonstration. Students of all ages will enjoy seeing this demonstration in action, but don't let them get close to it. Be sure to practice the timing of the '''Primary''' style before presenting this demonstration.

== Materials ==

* Potassium Permanganate
* Glycerin or Glycerol
* Scoopula
;Primary Presentation:
* Eyedropper
* Cork Base
* Large Watch Glass or Small Metal Bowl
;Alternative Presentation:
* Two Eyedroppers
* Metal Stand Base
* Two Medium Watch Glasses

== Safety Precautions ==

Please read the Fire Demonstration section of the [[Demonstration Safety]] page before performing this demonstration. Potassium Permanganate is toxic if ingested and can oxidize tissue, so avoid direct contact with the powder. After the reaction completes, it can be safely washed down a drain, but continue to wear gloves in case of any non-reacted powder.

This demonstration requires: safety glasses, rubber or nylon gloves, blast shield

== Demonstration ==

;Primary Presentation:
# Set the watch glass or bowl on the cork base, and have the blast shield in front of it. Use the scoopula to put a small pile of potassium permanaganate (KMnO<sub>4</sub>) in the middle of the dish, and make a small indentation in the center of the pile. 
# Explain what KMnO<sub>4</sub> is to the audience, and introduce redox reactions. Ask students for ideas on what they think will happen when you add the glycerin/glycerol to the bowl.
# The next part of this demonstration requires careful timing. Put a small drop of the glycerin/glycerol into the dish, in the indentation of the pile. Immediately go into the following explanation:
#* "When KMnO<sub>4</sub> mixes with glycerin/glycerol, a redox reaction starts. This reaction starts out really slow, but produces a lot of heat, so it will start to speed up bit by bit. As the KMnO<sub>4</sub> oxidizes the sugar, it will speed up more and more until it finally starts to smoke, and after that it will ignite!"
#* The reaction takes 10-15 seconds to ignite, depending on outside temperature and the temperature of the glycerin/glycerol. If timed carefully, the reaction will start smoking when you say "until it finally starts to smoke", and then ignite 1-2 seconds later!
# After applause, ask students if they can guess why it starts slowly. For an older audience, you can use a whiteboard to draw the reaction, and point out the large amount of KMnO<sub>4</sub> needed to start the reaction.

;Alternate Presentation:
# Set the two watch glasses next to each other on the metal stand base, and have the blast shield in front of it. Use the scoopula to put a small pile of potassium permanaganate (KMnO<sub>4</sub>) in the middle of each, and make a small indentation in the center of one pile. 
# Explain what KMnO<sub>4</sub> is to the audience. Ask students for ideas on what they think will happen when you add the glycerin/glycerol. Also ask if they think ''where'' you put the sugar will affect how fast it goes.
# Put a small drop of the glycerin/glycerol into each dish. In the untouched dish, put the drop on the side of the mound, with it only partially touching the powder. In the dish with the indentation, put the drop in the center. Do this step quickly!
# Ask the audience to vote on which one they think will ignite first. As you do this, the one with the indent will start smoking, and then ignite! the other will do the same, but after the first is already lit.
# After applause, ask students why the placement of the sugar affects the rate of reaction. Discuss.

== Why This Works ==

===Short Explanation===
Reduction-Oxidation Reactions, or ''Redox Reactions'', are reactions that involve a transfer of electrons. ''Oxidizers'' such as Potassium Permanganate (KMnO<sub>4</sub>) take electrons, while ''Reducers'' such as Glycerin and Glycerol give electrons. This means that our glycerin/glycerol is ''Oxidized'', or loss electrons, and our KMnO<sub>4</sub> is ''Reduced'', or has gained electrons. An easy way to remember this is "'''LEO''' says '''GER'''", where '''LEO''' means '''L'''oss '''E'''quals '''O'''xidation and '''GER''' means '''G'''ain '''E'''quals '''R'''eduction.

In both styles for this reaction, we see that it takes a little while for it to start. This is because the ''Rate of Reaction'', or how quickly this reaction happens, relies heavily on the physical properties of the chemicals. This reaction needs to have a lot of the KMnO<sub>4</sub> powder in contact with the glycerin/glycerol in order to react. If there isn't enough of each in contact, then it reacts very slowly, like if the glycerin/glycerol is on the side of the pile. If there is a lot of each in contact, then it will react faster, like putting the glycerin/glycerol in the middle of the powder. This reaction also needs a lot of energy to start, but releases a lot of heat at the end. This is why the temperature of the reactants plays a big role on how fast it will react!

===Full Explanation===


Reduction-Oxidation Reactions, or ''Redox Reactions'', are reactions that involve a transfer of electrons. ''Oxidizers'' such as Potassium Permanganate (KMnO<sub>4</sub>) take electrons, while ''Reducers'' such as Glycerin and Glycerol give electrons. When electrons are transferred between the reactants, it is usually by the transfer of oxygen atoms. This means that our glycerin/glycerol is ''Oxidized'', or our KMnO<sub>4</sub> is ''Reduced'', Then one can see it as glycerin would receive oxygen atoms from the KMnO<sub>4</sub>. The KMnO<sub>4</sub> is then "reduced", losing oxygen atoms, while the glycerin is "oxidized" or gains oxygen atoms.

The reaction between KMnO<sub>4</sub> and Glycerin goes as follows:
{| class="wikitable" style="color:black; background-color:#ddd; text-align: center; margin-right: auto"
|14 KMnO<sub>4</sub> + 3 C<sub>3</sub>H<sub>8</sub>O<sub>3</sub> ⇒ 14 MnO<sub>2</sub> + 7 K<sub>2</sub>CO<sub>3</sub> + 2 CO<sub>2</sub> + 12 H<sub>2</sub>O
|}

This reaction requires a large amount of KMnO<sub>4</sub> for it to progress. This is part of why the ''Rate of Reaction'', or time it takes a reaction to complete, is slow for this particular reaction. The rate of reaction can be affected by a large number of factors, such as the temperature, the amount of each reactant, and how well the reactants are mixed. This is explored with the two methods of presenting this demonstration.

* In the '''Primary''' Method, we rely on the slow rate of the reaction to get the dramatic effect for the presentation. The glycerin is poured onto the KMnO<sub>4</sub> powder, and they start to react. However, it takes time for it to react, since the glycerin absorbs much of the heat generated. The reaction creates a lot of heat, which is why it ultimately results in a bright flash of sparks. But it takes time for it to create the heat, and so the presenter has time to provide an explanation of the steps in the reaction. Once it starts to smoke, the smoke helps to carry away the produced water and carbon dioxide, as well as any waste carbon produced in the burning of glycerin. Then, when it ignites, the whole pile will react quickly, having a large amount of extra heat to push the reaction along.
* In the '''Alternative''' Method, we are showcasing how the mixing of the reactants affects the rate of reaction. One of the watch glasses has the reactants in direct contact, while the other has the reactants next to each other. As is expected, the reactants that are in direct contact will ignite much faster than the ones which are not. The physical chemistry of a reaction is important when it comes to the reaction's pace, and if the reactants are never mixed, they will have no reason to react.

== Additional Information ==

* This demonstration pairs well with the [[Elephant Toothpaste]] and the [[Shaking Solution]] demonstrations.
* This demonstration is a part of the [[Fire and Ice Show]].

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== What to Say ==

Here we have two chemicals—we’re going to combine them and observe the reaction between them. The powder is potassium permanganate, (place some onto the watch glasses) and this clear, gooey liquid is called glycerin or glycerol. (gesture to other watch glass) What we’re going to observe is something called a redox reaction. That means that in the reaction, one of the chemicals, the reducing agent, in this case; glycerol, is doing okay, but it has a lot of electrons it’s juggling, and would be pretty glad if it could get rid of some of them. The other chemical, potassium permanganate, is called an oxidizing agent, which means that it would be more than happy to grab up some extra electrons. When they mix a reducing-oxidation reaction will take place; Chemists shorten that and call it a redox reaction. (Probably because it’s easier to say and sounds way cooler.)

You’ll observe that the reaction between these two chemicals will also be exothermic. If you look at the different parts of that word, you can understand what it means: “exo” means out (think exoskeletons on insects) and “thermic” means it involves heat, so an exothermic reaction is one that releases a lot of heat. (Add the glycerin to the KMn04.) We’re going to set up two dishes to watch this experiment. You’ll notice that in one dish, we put a little dimple into the pile of potassium permanganate, and placed the glycerol directly in the middle, while in the other one we put the glycerol off to the side a little. Which one do you think will react first? (Get answers, ask students why they think that, then watch to see what happens—hopefully the dimpled pile will react first.) What we were looking at with the two different reactions was to see how the surface area of where the two substances come into contact affects how fast they react. In the pile with the dimple, the glycerol was cradled by the potassium permanganate, they were touching all around, but in the other, they were just touching a little on the side. The experiment where they were touching more reacted faster.

A useful metaphor to understand what happened is this: imagine that there are two groups of people, one with candy and one without, and the people with candy want to give it to the people that don’t have it. Now, if the two groups just rush together in a big mob and hand over the candy all at once, it will get done a lot faster than if they stood in a single file line and gave pieces of candy to each other one by one. The experiment where the reactants were just touching on the side was like that single file line: if there isn’t much area to for electrons to get passed between the glycerol and potassium permanganate, the reaction isn’t going to happen very fast. That’s why more surface area makes the reaction proceed more quickly.

== Why It Is ==

Any chemical reaction that results in atoms having their oxidation numbers changed is called a redox (reduction-oxidation) reaction. Oxidation describes either the loss of electrons or hydrogen, or the increase of oxygen or oxidation state of a molecule. Reduction describes the gain of electrons or hydrogen or the loss of oxygen or decrease of the oxidation state of a molecule. It is not entirely accurate, but the reaction can be roughly described by saying that the Oxidizing agent (potassium permanganate) “wants” more electrons and accepts them from the Reducing agent (glycerol) which wants to give them up. The reaction that takes places is:

14 KMnO4(s) + 4 C3H5(OH)3(l) à 7 K2CO3(s) + 5 CO2(g) + 16 H2O(g) + Mn2O3(s)

== Real Life Examples ==

Potassium permanganate, KMnO4, has many uses, both everyday and scientific. It is used for water treatment to remove iron and hydrogen sulfide, which makes a rotten egg smell, from swimming pools and waste water. Dilute solutions of it are used in disinfectants for treating canker sores, hand sanitizers, and for treating fungal infections of the hands and feet. It is also used in chemistry for both quantitative and qualitative tests, such as redox titrations. KMnO4 was used in the past as a component of flash powder, which is used in fireworks, explosives, and old fashioned photography. This is no longer the case, as there are other compounds that are more stable and reliable for these purposes than potassium permanganate.

Glycerol, C3H5(OH)3, is also called glycerin or glycerine.It is relatively common, and you migh recognize the name from the ingredient lists of many foods and toiletries. In food, glycerol is used as a solvent and sweetener, as well as a preservative and an agent for keeping food moist. It is also used to produce nitroglycerin, an explosive. In pharmaceutical products, glycerol is used primarily as a lubricant to improve smoothness. It is found in cough syrups, toothpaste, shaving cream, soaps, and hair care products.

Redox reactions are important in many biological processes. Ex: the oxidation of glucose and reduction of oxygen to water ins cellular respiration.

The reaction in this demo was apparently used to start a fire once on the TV show Survivor Man, but it is not a common practice.(A lighter would probably be way more reliable and it won't turn your hands purple!) A forum discussing this: http://episteme.arstechnica.com/eve/forums/a/tpc/f/770002407831/m/857005467831
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