Potassium Permanganate And Glycerin: Difference between revisions
Jump to navigation
Jump to search
imported>Stwikiadmin No edit summary |
imported>Stwikiadmin |
||
| (2 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
== | {| 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]]. | |||
<!-- | |||
== What to Say == | == What to Say == | ||
| Line 60: | Line 100: | ||
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 | 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 | ||
--> | |||
Latest revision as of 17:54, 9 November 2016
| 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 (KMnO4) in the middle of the dish, and make a small indentation in the center of the pile.
- Explain what KMnO4 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 KMnO4 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 KMnO4 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 KMnO4 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 (KMnO4) in the middle of each, and make a small indentation in the center of one pile.
- Explain what KMnO4 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 (KMnO4) take electrons, while Reducers such as Glycerin and Glycerol give electrons. This means that our glycerin/glycerol is Oxidized, or loss electrons, and our KMnO4 is Reduced, or has gained electrons. An easy way to remember this is "LEO says GER", where LEO means Loss Equals Oxidation and GER means Gain Equals Reduction.
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 KMnO4 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 (KMnO4) 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 KMnO4 is Reduced, Then one can see it as glycerin would receive oxygen atoms from the KMnO4. The KMnO4 is then "reduced", losing oxygen atoms, while the glycerin is "oxidized" or gains oxygen atoms.
The reaction between KMnO4 and Glycerin goes as follows:
| 14 KMnO4 + 3 C3H8O3 ⇒ 14 MnO2 + 7 K2CO3 + 2 CO2 + 12 H2O |
This reaction requires a large amount of KMnO4 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 KMnO4 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.