Halloween Reaction or Old Nassau Reaction
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Halloween Reaction or Old Nassau Reaction
Orange and Black Clock Reaction
By Anne Marie Helmenstine, Ph.D., About.com
The Old Nassau or Halloween reaction is a clock reaction in which the color of a chemical solution changes from orange to black. Here's how you can do this reaction as a chemistry demonstration and a look at the chemical reactions that are involved.
Halloween Reaction Materials
* water
* soluble starch
* sodium metabisulphite (Na2S2O5)
* mercury(II) chloride
* potassium iodate (KIO3)
Prepare the Solutions
* Solution A: Mix 4 g soluble starch in a couple milliliters of water. Stir the starch paste into 500 ml boiling water. Allow the mixture to cool to room temperature. Add 13.7 g of sodium metabisulphite. Add water to make 1 liter of solution.
* Solution B: Dissolve 3 g mercury(II) chloride in water. Add water to make 1 liter of solution.
* Solution C: Dissolve 15 g potassium iodate in water. Add water to make 1 liter of solution.
Perform the Demonstration
1. Mix 50 ml solution A with 50 ml of solution B.
2. Pour this mixture into 50 ml of solution C.
The color of the mixture will change to an opaque orange color after a few seconds as the mercury iodide precipitates. After another few seconds the mixture will turn blue-black as the starch-iodine complex forms.
If you dilute the solutions by a factor of two then it takes longer for the color changes to occur. If you use a smaller volume of solution B the reaction will proceed more rapidly.
Chemical Reactions
1. Sodium metabisulfite and water react to form sodium hydrogen sulfite:
Na2S2O5 + H2O --> 2 NaHSO3
2. Iodate(V) ions are reduced to iodide ions by the hydrogen sulfite ions:
IO3- + 3 HSO3- --> I- + 3 SO42- + 3 H+
3. When the concentration of iodide ions becomes sufficent for the solubility product of the HgI2 to exceed 4.5 x 10-29 mol3 dm-9, then orange mercury(II) iodide precipitates until the Hg2+ ions are consumed (assuming an excess of I- ions):
Hg2+ + 2 I- --> HgI2 (orange or yellow)
4. If I- and IO3- ions remain, then an iodide-iodate reaction takes place:
IO3- + 5 I- + 6 H+ --> 3 I2 + 3 H2O
5. The resulting statch-iodine complex is black to blue-black:
I2 + starch --> a blue/black complex
Orange and Black Clock Reaction
By Anne Marie Helmenstine, Ph.D., About.com
The Old Nassau or Halloween reaction is a clock reaction in which the color of a chemical solution changes from orange to black. Here's how you can do this reaction as a chemistry demonstration and a look at the chemical reactions that are involved.
Halloween Reaction Materials
* water
* soluble starch
* sodium metabisulphite (Na2S2O5)
* mercury(II) chloride
* potassium iodate (KIO3)
Prepare the Solutions
* Solution A: Mix 4 g soluble starch in a couple milliliters of water. Stir the starch paste into 500 ml boiling water. Allow the mixture to cool to room temperature. Add 13.7 g of sodium metabisulphite. Add water to make 1 liter of solution.
* Solution B: Dissolve 3 g mercury(II) chloride in water. Add water to make 1 liter of solution.
* Solution C: Dissolve 15 g potassium iodate in water. Add water to make 1 liter of solution.
Perform the Demonstration
1. Mix 50 ml solution A with 50 ml of solution B.
2. Pour this mixture into 50 ml of solution C.
The color of the mixture will change to an opaque orange color after a few seconds as the mercury iodide precipitates. After another few seconds the mixture will turn blue-black as the starch-iodine complex forms.
If you dilute the solutions by a factor of two then it takes longer for the color changes to occur. If you use a smaller volume of solution B the reaction will proceed more rapidly.
Chemical Reactions
1. Sodium metabisulfite and water react to form sodium hydrogen sulfite:
Na2S2O5 + H2O --> 2 NaHSO3
2. Iodate(V) ions are reduced to iodide ions by the hydrogen sulfite ions:
IO3- + 3 HSO3- --> I- + 3 SO42- + 3 H+
3. When the concentration of iodide ions becomes sufficent for the solubility product of the HgI2 to exceed 4.5 x 10-29 mol3 dm-9, then orange mercury(II) iodide precipitates until the Hg2+ ions are consumed (assuming an excess of I- ions):
Hg2+ + 2 I- --> HgI2 (orange or yellow)
4. If I- and IO3- ions remain, then an iodide-iodate reaction takes place:
IO3- + 5 I- + 6 H+ --> 3 I2 + 3 H2O
5. The resulting statch-iodine complex is black to blue-black:
I2 + starch --> a blue/black complex
Label:
Make Fake Blood
What You Need:
* 1 c (250mL) peanut butter
* 1 qt. (1 L) corn syrup
* 1/2 cup (125mL) soap
* 1 oz (30mL) red color
* 15 drops blue food color
Here's How:
1. Mix creamy peanut butter with a sufficient amount of white corn syrup to make a runny mixture.
2. Add (non-sudsy) soap and food colors and mix well.
3. Stir more corn syrup in until the desired consistency is reached.
4. Refrigerate unused blood in an airtight container.
Tips:
1. Inexpensive white corn syrup is said to be thicker and more suitable for the fake blood than its costlier relatives.
* 1 c (250mL) peanut butter
* 1 qt. (1 L) corn syrup
* 1/2 cup (125mL) soap
* 1 oz (30mL) red color
* 15 drops blue food color
Here's How:
1. Mix creamy peanut butter with a sufficient amount of white corn syrup to make a runny mixture.
2. Add (non-sudsy) soap and food colors and mix well.
3. Stir more corn syrup in until the desired consistency is reached.
4. Refrigerate unused blood in an airtight container.
Tips:
1. Inexpensive white corn syrup is said to be thicker and more suitable for the fake blood than its costlier relatives.
Absorb Chemistry
Absorb Chemistry is an interactive course written by Lawrie Ryan, the best selling author of 'Chemistry for You'. It's ideal for use on a whiteboard in front of a whole class or by students by themselves.
Absorb Chemistry is divided into units, so you can follow the course all the way through, or use the units individually. Each unit provides a compelling narrative supported by interactive animations, our unique simulations, videos of key experiments, and exercises to ensure concepts have been understood.
Try the free sample units in your class. Also try downloading SCORM-compliant sample units for use in your VLE or learning management system.
Absorb Chemistry Resources
If you are disappointed with the quality of free resources that can be downloaded from the internet, then maybe Absorb Chemistry Resources with over 300 high quality resources (videos, graphics and animations) is what you need. Perfect for creating your own whiteboard presentations.
Absorb Chemistry Resources is a lower cost alternative to Absorb Chemistry that allows you to view or download the resources but not to view or download units from Absorb Chemistry.
Use downloaded resources:
* in PowerPoint presentations;
* with whiteboard authoring software provided by companies such as Promethean or Smart;
* in VLEs or Learning Management Systems;
* offline, in a classroom without an internet connection.
Free Resources
You can view the resources from Absorb Chemistry online free of charge. Over 250,000 users have benefited from this service already, testament to the quality of Absorb. Click here to search for free resources.
Why are they free?
Because we're sure that once you've used them online you'll want to buy Absorb Chemistry Resources, so that you can download them and make your own presentations!
Absorb Chemistry is divided into units, so you can follow the course all the way through, or use the units individually. Each unit provides a compelling narrative supported by interactive animations, our unique simulations, videos of key experiments, and exercises to ensure concepts have been understood.
Try the free sample units in your class. Also try downloading SCORM-compliant sample units for use in your VLE or learning management system.
Absorb Chemistry Resources
If you are disappointed with the quality of free resources that can be downloaded from the internet, then maybe Absorb Chemistry Resources with over 300 high quality resources (videos, graphics and animations) is what you need. Perfect for creating your own whiteboard presentations.
Absorb Chemistry Resources is a lower cost alternative to Absorb Chemistry that allows you to view or download the resources but not to view or download units from Absorb Chemistry.
Use downloaded resources:
* in PowerPoint presentations;
* with whiteboard authoring software provided by companies such as Promethean or Smart;
* in VLEs or Learning Management Systems;
* offline, in a classroom without an internet connection.
Free Resources
You can view the resources from Absorb Chemistry online free of charge. Over 250,000 users have benefited from this service already, testament to the quality of Absorb. Click here to search for free resources.
Why are they free?
Because we're sure that once you've used them online you'll want to buy Absorb Chemistry Resources, so that you can download them and make your own presentations!
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