Elephant Toothpaste: Difference between revisions

From Science Theatre
Jump to navigation Jump to search
← Older edit
imported>Stwikiadmin
VisualWikitext
imported>Stwikiadmin
Created page with "== Age == Middle School, High School == Format == Stage Show == Materials == 100 mL or 1 L graduated cylinder Dish soap 30% Hydrogen peroxide (H2­O2) Food c..."
imported>Stwikiadmin
mNo edit summary
 
(One intermediate revision by the same user not shown)
Line 1: Line 1:
== Age ==
{| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
| [[Chemistry]]:
| Catalysts, Exothermic Reactions
|-
| Grade Range:
| [[Elementary School]], [[Middle School]], [[High School]]
|-
| Format:
| [[Stage]]
|}


Middle School, High School
This is a classic demonstration, which students of all ages love to watch happen. Be sure to use some food dye for some added flair!
 
== Format ==
 
Stage Show


== Materials ==
== Materials ==


    100 mL or 1 L graduated cylinder
* 30% Hydrogen Peroxide
    Dish soap
* Potassium Iodide (KI) Solution
    30% Hydrogen peroxide (H2­O2)
* 500mL Graduated Cylinder or Erlenmeyer Flask
    Food coloring
* Soap
    50 mL centrifuge tube
* Food Dye
    Saturated potassium iodide (KI) solution (100 g KI to 70 mL water)
* 50mL Centrifuge Tube
    Garbage bags or tarp
* Large Clear Bin
    Small fish tank


== Safety Precautions ==
== Safety Precautions ==


Science Theatre demonstrators must keep the safety of themselves and their audience in mind at all times. All Science Theatre demonstrators must have read through the Safety Training page. The ST Safety Box with first aid kit, fire extinguisher, etc. should always be available to demonstrators. Always wear safety gloves, glasses, and a labcoat if handling chemicals; always perform potentially dangerous demonstrations at a safe distance from the audience; and always keep a very close eye on any volunteers you call from the audience.
Please read the Liquid Chemical section of the [[Demonstration Safety]] page before performing this demonstration.
 
Hydrogen peroxide is a strong oxidizer, do not allow it to touch your skin. Do not allow any KI to get onto your skin. It will stain your clothes permanently. Wear gloves, goggles, and perhaps a labcoat. When performing the exothermic reaction ensure that observers are about four feet away. DO NOT allow children to touch the “toothpaste.”
 
[http://www.sciencelab.com/msds.php?msdsId=9924299: 30% Hydrogen Peroxide MSDS]


[http://www.sciencelab.com/msds.php?msdsId=9926001: Potassium Iodide MSDS]
This demonstration requires: safety glasses or goggles, rubber or latex gloves.
 
== Preparation ==
 
Ensure prior to your show that you have enough saturated KI solution and hydrogen peroxide. Immediately before your show, lay out garbage bags (or tarp) under your experiment area. Half fill small fish tank with water, so you can clean out the graduated cylinder between presentations.


== Demonstration ==
== Demonstration ==


Pour about 20 mL (1/5 of the total volume of the cylinder) of hydrogen peroxide into the cylinder. Pour about 5 mL of soap into the 100 mL graduated cylinder. Then add 4 drops of food coloring. Measure out about 5 mL of KI solution. Ensure that people are standing a safe distance away. Then, add the KI to the graduated cylinder, and step back. Note the steam coming off the foam produced by the O2 gas.
;Preparation: 24 hours before the event, be sure to check if there is enough of the KI solution. If there is not, follow these steps to prepare it:
 
# Get a 500g bottle of KI. Get a 1L beaker and a hot plate, and start warming 500mL of water on the hot plate set to medium.  
== What to Say ==
# When the water is hot, add the KI in increments, waiting for the previous addition to dissolve fully until adding more. Once all of it has been added, fill the 500G bottle of KI 2/3 with water, close it and shake it to get the last of the KI from the container. Pour this into the 1L beaker and stir.
 
# Fill the KI solution bottles with the still-hot solution, close them, and let them cool to room temperature on a table or counter. Label the bottles with the month and year, and your initials.
Pour the hydrogen peroxide into the cylinder and explain that a reaction is going on... can you see it? Probably not - even though hydrogen peroxide is constantly decomposing into water (H2O) and oxygen gas (O2), it goes so slowly that it looks like nothing is happening.
 
We can use a catalyst to make this reaction more exciting! A catalyst is a chemical that speeds up a reaction, but doesn't actually get used up. Think of the chemical reaction like trying to walk up big hill. It takes a lot of energy to get up that hill, so you will walk (you can act out walking up a hill). If there was a tunnel through the hill, you could walk through it a lot faster and use a lot less energy (act out easy walking). Adding a catalyst is like blasting a tunnel through a big hill - it makes the reaction go faster because it takes less energy! For older audiences, you can draw out a reaction coordinate diagram (see below).
 
Before you add the KI have the kids give you a 3, 2, 1 countdown. Then add the catalyst. Have them note that the “toothpaste” is smoking. The oxygen that was released is the gas trapped within the soap, making the bubbles. Depending on the age of the audience you could discuss exothermic reactions, and how they give off heat. This occurs because the water and oxygen that the hydrogen peroxide breaks down into are more stable than its original peroxide form. Therefore the excess energy is released in the form of heat. To prove that oxygen is present in the mixture you may take a glowing splint and stick it into the foam and it will light - do this with great caution!
 
== Why It Is ==


The whole premise behind using catalysts is that they lower the amount of energy you need to put into a reaction for it to occur. In an uncatalyzed reaction you have to put in a significant amount more energy, activation energy, in order to initiate the reaction. However, upon the addition of a catalyst the activation energy of the reaction is lowered because the catalyst offers a different mechanism of achieving the transition state between the reactants and products. Thus, not as much energy has to be expended to convert the reactants to the transition state and then to the products.
;Presentation: ''Note: do NOT handle the chemicals in this show unless you are wearing gloves and glasses/goggles.''
# Set out the clear bin with the graduated cylinder in the center. Measure out 100mL of the hydrogen peroxide into the cylinder.
# Ask the audience if they have ever heard of hydrogen peroxide. Likely they have, and explain that it is sometimes used to clean cuts or for bleaching hair. State that the hydrogen peroxide we are using is ten times stronger than what they have at home, and it can be dangerous, so to not try this at home.
# Add a small amount of liquid soap to the cylinder, and a couple drops of food dye. After doing so, swirl the cylinder to mix them in and point out that hydrogen peroxide reacts with light, so it is breaking down as we speak.
#*''Note: Be dramatic when saying that it is breaking down! Act like it is exploding the moment you say this, and give the audience a few seconds to laugh at your overreaction.''
# Point out that it is a slow reaction, and show the catalyst that you will be adding in. Measure out 10mL of the catalyst using the centrifuge tube, and then ask for a countdown. Pour it in at the end of the countdown, and watch as it turns into a big pile of bubbles!
# Use the rising steam from the reaction to introduce the term "exothermic". Finish by explaining how the catalyst made the reaction faster, using either the [[#Hill Metaphor]] or the [[#Race Metaphor]] for younger audiences.


== Real Life Examples ==
== Why This Works ==


Some products that are made in a process involving a catalyst include:
{| class="wikitable" style="color:black; background-color:#ddd; text-align: center; margin-left: 24px; float:right"
|+ Hydrogen Peroxide Reaction
|Without Catalyst||2 H<sub>2</sub>O<sub>2</sub> ---> 2 H<sub>2</sub>O + O<sub>2</sub>
|-
|With Catalyst
|H<sub>2</sub>O<sub>2</sub> + I<sup>-</sup> ---> H<sub>2</sub>O + IO<sup>-</sup>
H<sub>2</sub>O<sub>2</sub> + IO<sup>-</sup> ---> H<sub>2</sub>O + O<sub>2</sub> + I<sup>-</sup>
|}


    Garbage bags
Hydrogen Peroxide (H<sub>2</sub>O<sub>2</sub>) is a very reactive molecule, and breaks down into water and oxygen gas. When exposed to light it will break down, but this happens very slowly. This is why we include our catalyst, Potassium Iodide (KI). A ''Catalyst'' is a molecule that will help another reaction go faster, without being used up in the process. This means that at the end of the reaction, we could get back all of the catalyst that we used in the reaction, which we see as the yellow-brown discoloration in the bubbles.
    Grocery bags
    Squeezable bottles


These are all made from polyethylene, which is polymerizes by passing ethylene gas over a catalyst. Most other polymers are made in the same (or similar) way. Synthetic rubber, nylon, Polyester, PVC, Teflon. These are used to produce:
The Hydrogen Peroxide reaction releases a lot of energy, which we see as the steam that is rising out of the bubbles. This means that this is an ''Exothermic'' reaction. A way to explain this is by breaking down the word "exothermic" for the audience. "Exo" they may have heard before, such as an ''exo''skeleton, and it sounds similar to "exit". "Thermic" is similar to "Thermo", like in thermometer, and refers to heat. So by breaking the word down we can see that exothermic means to have heat exit, or leave, the reaction.  


    bouncy balls
====Hill Metaphor====
    pantyhose
Imagine that you are on one side of a big hill. On the other side of this hill is a party that you want to go to, but to get there you have to climb all the way up the hill and all the way down the other side. All of that climbing is going to tire you out, and you'll use up all of your energy before getting to the party. So let's imagine that you find a tunnel that goes right through the hill. This tunnel makes it possible for you to get to the other side pretty quickly, and you won't be tired when you get to the party. When you use the tunnel, does it magically disappear? No! The tunnel is still there, so anyone else who also needs to go over the hill to the party can also use the tunnel to get there!
    cell-phone and laptop cases
    rain coats
    water pipes
    non-stick surfaces and pads
    saran wrap
    food containers
    cheap wigs
    fishing line


Catalytic converters are platinum and rhodium - based pollution scrubbers in car exhausts.
The "hill" is the amount of energy needed for the reaction to take place, and the "tunnel" is our catalyst that we add. Before adding it, the reaction needs a lot of energy to take place, and so it goes very slowly. Once we add a catalyst though, the reaction can now take this lower energy path, and happens very quickly!


The "haber process", a well known catalytic reaction, is used to produce the nitrogen used in most modern-day fertilizer.
====Race Metaphor====
Imagine that you are in a race with some of your friends. You are going to run from one end of the park to the other, which both of you know will be tiring. Just before the race though, you get a bicycle to use for the race. By using the bike, do you think you will be faster than your friends? Of course! Not only that, but you will be less tired at the end of the race. When you finish the race, does your bike suddenly disappear? Nope, the bike is still there!


Laundry detergent often contain active enzymes (organic catalysts) that speed up cleaning by breaking down certain compounds.
The "race" is the amount of energy needed for the reaction to take place, and the "bicycle" is our catalyst we add. Before adding it, the reaction will take a lot of energy to move forward, and so it goes slowly. Once we add in a catalyst, the reaction can now move much faster!


Beer and bread are typically made with yeast, a living organism containing enzymes.
== Additional Information ==


Finally, the human body itself couldn't work without enzymes – they're used by cells to grow, reproduce, and create energy.
* Catalysts are common in many things, including:
** Catalytic converters in cars to help remove pollutants from car exhaust.
** The Haber Process for adding nitrogen into fertilizer.
** Yeast contain enzymes, which speed up the bread and beer making processes.
** We have enzymes in our digestive tracts, which break down food for us!
* This demonstration pairs well with the [[Shaking Solution]] and the [[Endothermic Reactions]] demonstrations.
* This demonstration is a part of the [[Chemistry Show]].

Latest revision as of 21:47, 7 June 2016

Chemistry: Catalysts, Exothermic Reactions
Grade Range: Elementary School, Middle School, High School
Format: Stage

This is a classic demonstration, which students of all ages love to watch happen. Be sure to use some food dye for some added flair!

Materials

  • 30% Hydrogen Peroxide
  • Potassium Iodide (KI) Solution
  • 500mL Graduated Cylinder or Erlenmeyer Flask
  • Soap
  • Food Dye
  • 50mL Centrifuge Tube
  • Large Clear Bin

Safety Precautions

Please read the Liquid Chemical section of the Demonstration Safety page before performing this demonstration.

This demonstration requires: safety glasses or goggles, rubber or latex gloves.

Demonstration

Preparation
24 hours before the event, be sure to check if there is enough of the KI solution. If there is not, follow these steps to prepare it:
  1. Get a 500g bottle of KI. Get a 1L beaker and a hot plate, and start warming 500mL of water on the hot plate set to medium.
  2. When the water is hot, add the KI in increments, waiting for the previous addition to dissolve fully until adding more. Once all of it has been added, fill the 500G bottle of KI 2/3 with water, close it and shake it to get the last of the KI from the container. Pour this into the 1L beaker and stir.
  3. Fill the KI solution bottles with the still-hot solution, close them, and let them cool to room temperature on a table or counter. Label the bottles with the month and year, and your initials.
Presentation
Note: do NOT handle the chemicals in this show unless you are wearing gloves and glasses/goggles.
  1. Set out the clear bin with the graduated cylinder in the center. Measure out 100mL of the hydrogen peroxide into the cylinder.
  2. Ask the audience if they have ever heard of hydrogen peroxide. Likely they have, and explain that it is sometimes used to clean cuts or for bleaching hair. State that the hydrogen peroxide we are using is ten times stronger than what they have at home, and it can be dangerous, so to not try this at home.
  3. Add a small amount of liquid soap to the cylinder, and a couple drops of food dye. After doing so, swirl the cylinder to mix them in and point out that hydrogen peroxide reacts with light, so it is breaking down as we speak.
    • Note: Be dramatic when saying that it is breaking down! Act like it is exploding the moment you say this, and give the audience a few seconds to laugh at your overreaction.
  4. Point out that it is a slow reaction, and show the catalyst that you will be adding in. Measure out 10mL of the catalyst using the centrifuge tube, and then ask for a countdown. Pour it in at the end of the countdown, and watch as it turns into a big pile of bubbles!
  5. Use the rising steam from the reaction to introduce the term "exothermic". Finish by explaining how the catalyst made the reaction faster, using either the #Hill Metaphor or the #Race Metaphor for younger audiences.

Why This Works

Hydrogen Peroxide Reaction
Without Catalyst 2 H2O2 ---> 2 H2O + O2
With Catalyst H2O2 + I- ---> H2O + IO-

H2O2 + IO- ---> H2O + O2 + I-

Hydrogen Peroxide (H2O2) is a very reactive molecule, and breaks down into water and oxygen gas. When exposed to light it will break down, but this happens very slowly. This is why we include our catalyst, Potassium Iodide (KI). A Catalyst is a molecule that will help another reaction go faster, without being used up in the process. This means that at the end of the reaction, we could get back all of the catalyst that we used in the reaction, which we see as the yellow-brown discoloration in the bubbles.

The Hydrogen Peroxide reaction releases a lot of energy, which we see as the steam that is rising out of the bubbles. This means that this is an Exothermic reaction. A way to explain this is by breaking down the word "exothermic" for the audience. "Exo" they may have heard before, such as an exoskeleton, and it sounds similar to "exit". "Thermic" is similar to "Thermo", like in thermometer, and refers to heat. So by breaking the word down we can see that exothermic means to have heat exit, or leave, the reaction.

Hill Metaphor

Imagine that you are on one side of a big hill. On the other side of this hill is a party that you want to go to, but to get there you have to climb all the way up the hill and all the way down the other side. All of that climbing is going to tire you out, and you'll use up all of your energy before getting to the party. So let's imagine that you find a tunnel that goes right through the hill. This tunnel makes it possible for you to get to the other side pretty quickly, and you won't be tired when you get to the party. When you use the tunnel, does it magically disappear? No! The tunnel is still there, so anyone else who also needs to go over the hill to the party can also use the tunnel to get there!

The "hill" is the amount of energy needed for the reaction to take place, and the "tunnel" is our catalyst that we add. Before adding it, the reaction needs a lot of energy to take place, and so it goes very slowly. Once we add a catalyst though, the reaction can now take this lower energy path, and happens very quickly!

Race Metaphor

Imagine that you are in a race with some of your friends. You are going to run from one end of the park to the other, which both of you know will be tiring. Just before the race though, you get a bicycle to use for the race. By using the bike, do you think you will be faster than your friends? Of course! Not only that, but you will be less tired at the end of the race. When you finish the race, does your bike suddenly disappear? Nope, the bike is still there!

The "race" is the amount of energy needed for the reaction to take place, and the "bicycle" is our catalyst we add. Before adding it, the reaction will take a lot of energy to move forward, and so it goes slowly. Once we add in a catalyst, the reaction can now move much faster!

Additional Information

  • Catalysts are common in many things, including:
    • Catalytic converters in cars to help remove pollutants from car exhaust.
    • The Haber Process for adding nitrogen into fertilizer.
    • Yeast contain enzymes, which speed up the bread and beer making processes.
    • We have enzymes in our digestive tracts, which break down food for us!
  • This demonstration pairs well with the Shaking Solution and the Endothermic Reactions demonstrations.
  • This demonstration is a part of the Chemistry Show.
Retrieved from "https://sciencetheatre.kaedon.net/mediawiki/index.php?title=Elephant_Toothpaste&oldid=365"