Download MSTA WOW Chemistry

Put Some WOW in Chemistry with Demos
MSTA, October 26, 2009
Janet Wise and Dennis Reed
1.
2.
Density Adapted from http://www.stevespanglerscience.com/experiment/seven-layer-density-column
Atomic Structure—The Black Box
Ob-Scertainer Kit from Flinn, AP4549, $77.95 for set of 12
3. Old Foamey
Kit from Flinn, AP2085, $17.91
4. Freezing Point Depression
Concept: Observe the colligative property of freezing point depression by using rock salt to lower the freezing point of
water.
Materials: Crushed ice and rock salt
Procedure:
1. Fill two 400-mL beakers with crushed ice. Add 5 mL of cold tap water to each beaker.
2. Stir the contents of each beaker with a stirring rod until both beakers are at a constant temperature, approximately one
minute.
3. Measure the temperature of each beaker and record the readings.
4. Add 75 g of rock salt to one of the beakers. Continue stirring both beakers. Some of the salt will dissolve.
5. When the temperature in each beaker is constant, record the readings.
6. To clean up, flush the contents of each beaker down the drain with excess water.
(Instructions from Glencoe's Chemistry: Matter and Change, 2002)
5. Variations on a Flame Test (Instructions from Flinn)
A salt is dissolved in methanol. Upon combustion, a characteristic color is seen.
Concept: Methanol is flammable and when mixed with oxygen and ignited creates quite an explosion. When an atom's
electrons drop from the excited state to the ground state, a wavelength of light will be emitted. Metals have characteristic
emissions of light that can be used to identify the individual metal, much like fingerprints can identify people.
Materials:
1 gallon plastic milk jug with screw cap
Methanol (methyl alcohol)
Nitrate or chloride salt of Li, K, Ba, Sr, or Cu
Meter stick with candle or fireplace match attached
Safety Precautions:
Methanol is toxic by ingestion and very flammable. Make sure all excess methanol is removed from the bottle. Cap the
methanol bottle and remove it from demo area. Wear safety goggles.
Procedure:
1. Make a concentrated solution of methanol and a salt.
2. Pour about 5 mL of the methanol solution into the milk jug and swirl to cover the sides of the jug. Open the jug and pour
out excess methanol. Use a paper towel to remove excess methanol from the rim of the jug. This prevents flames that
can melt the plastic.
3. Set the bottle on the counter, away from any flammable material. Dim the lights. Cover your ears! At an arm's
length, bring a burning candle or match attached to a meter stick to a point about one inch above the mouth of the bottle.
POW!
6. The Surprising Line
Flinn Scientific, Inc., P.O. Box 219, Batavia, IL 60510-0219, 1-800-452-1261
Dennis Reed: [email protected]
Janet Wise: [email protected]
7 Layer Density Column
Objective:


Create a stacked column of densities using liquids with known densities.
Estimate the density of some unknown solids.
Materials:




Karo syrup or maple syrup
Water
Vegetable Oil
Dawn dish soap (blue)









Green Rubbing Isopropyl alcohol
Lamp Oil
Honey
Graduated Cylinder
Food Coloring




Clear plastic cups
Straws
Glass beads
Lead fishing
sinkers
Brass swivels
Plastic beads
Wood chips
Cork
Procedure:
1. Mix some water and food coloring in a plastic cup
2. If you lamp oil is green like the rubbing alcohol, then you need to add a
different shade of food coloring to a small amount in a plastic cup.
3. Pour about 10 mL of Honey down the center of the graduated cylinder and try not to let it run down the sides.
4. Add 10 mL of Karo syrup or maple syrup to the graduated cylinder and again try not to let it run down the sides of the
cylinder.
5. Now allow students to suggest which liquid they would like to go into the graduated cylinder. Pour each additional 10
mL of liquid in the cylinder by tilting the cylinder and allowing each to slowly run down the sides of the container. The
slow pour is essential to prevent mixing of the liquids.
6. Allow time for the liquids to settle after all have been added to the graduated cylinder.
7. Give the students the density numbers for each of the liquids and let them label the liquid layers with density values on a
drawing of the density column.
8. Find some solids small enough to drop in to the density column for students to estimate their densities as they settle in
the liquid column.
Data:

Adapted from
Material
Dark Karo or maple syrup
Light Karo syrup
Water
Gycerin
Vegetable Oil
Dawn (blue)
Isopropyl Alcohol
Lamp Oil
Honey
Baby Oil
Density g/cm3
1.37
1.33
1.00
1.26
0.91
1.03
0.87
0.80
1.36
0.82
http://www.stevespanglerscience.com/experiment/seven-layer-density-column
The Surprising Line
"If the facts don't fit the theory, change the facts.—Albert Einstein
Introduction:
When precipitation reactions occur too fast and too easy, you could be missing a lot of good chemistry!
Materials:
Petri dishes (6—8 cm diameter)
Potassium chromate (s)
Distilled water
Micro spatulas (Flinn #AP9015
Lead(II) nitrate (s)
Overhead projector
Potassium iodide (s)
Safety Precautions:
Lead nitrate is moderately toxic by ingestion; strong oxidant; a body tissue irritant; and a possible carcinogen.
Potassium chromate is highly toxic by ingestion; harmful to skin, eyes, and respiratory tract; corrosive to body tissue;
and a known carcinogen. Follow Flinn's safety guidelines for all chemical disposal. Wear chemical splash goggles,
chemical-resistant gloves, and a chemical-resistant apron. Please consult Material Safety Data Sheets for further safety,
handling, and disposal information.
Procedure:
1. Place a thin layer of distilled water in a Petri dish and place the dish on a perfectly horizontal overhead projector.
2. Carefully add a small amount of the lead (Il) nitrate crystals into the water close to the side of the dish.
3. With a clean spatula, add solid potassium iodide to the exact opposite side of the Petri dish.
4. Watch carefully as a thin line appears and then grows. Repeat the procedure using lead (II) nitrate and potassium
chromate.
Discussion:
Using this method to precipitate lead (II) iodide and lead (II) chromate allows students to analyze the process
occurring. They can follow the dissolution, the migration of ions (related to size), and the precipitation reaction.
Reference:
deVos, Wobbe and Verdonk, A., "A New Road to Reactions," Journal of Chemical Education, August 1985, pp
648-9.
Flinn Scientific Foundation
39
Old Foamey
Chemistry Demonstration Kit
Introduction
Mix together hydrogen peroxide, sodium iodide solution, and dishwashing liquid in a tall cylinder and stand back. Your students
will observe with amazement a catalyst in action as an enormous amount of soapy foam erupts from "Old Foamey!"
Chemical Concepts
• Catalysts
• Decomposition Reactions
Materials Needed (for each demonstration)
Hydrogen peroxide, 30%, 20 mL*
Sodium iodide solution, 2 M, 5 mL*
Dishwashing liquid (Dove®), 10 mL*
*Materials included in kit.
Food coloring (optional)
Graduated cylinder, 100-mL
Graduated cylinder, 10-mL
Plastic tray, several inches deep
Safety Precautions
Hydrogen peroxide, 30%, will act as an oxidizing agent with practically any substance. This substance is severely corrosive to the
skin, eyes and respiratory tract; a very strong oxidant; and a dangerous fire and explosion risk. Do not heat this substance. Sodium
iodide is slightly toxic by ingestion. Although the dishwashing liquid is considered non-hazardous, do not ingest the material. Do
not stand over the reaction; steam and oxygen are produced quickly. Wear appropriate chemical splash goggles, chemical-resistant
gloves and a chemical-resistant apron. This activity requires the use of hazardous components and/or has the potential for hazardous
reactions. Please review current Material Safety Data Sheets for additional safety, handling, and disposal information.
Procedure
1. Place a 100-mL graduated cylinder in a plastic tray that is several inches deep.
2. Measure out 20 mL of the 30% hydrogen peroxide into the 100-mL graduated cylinder. Caution: Wear chemical resistant gloves
and goggles when handling 30% hydrogen peroxide. Contact with skin may cause burns.
3. Measure out 10 mL of dishwashing liquid into the 10-mL graduated cylinder and add it to the cylinder containing the
hydrogen peroxide. Add a few drops of food coloring, if desired. Have your students observe that little or no reaction occurs.
4. Measure out 5 mL of sodium iodide solution using the 10-mL graduated cylinder. Quickly but carefully, add the sodium iodide
solution to the 100-mL graduated cylinder.
5. Step back and observe the reaction.
Disposal
The foam and solution left in the cylinder may be rinsed down the drain with excess water.
Tips
You may want to do this demonstration in the laboratory sink since there is a lot of foam produced. Cleanup, however, is easy
due to the presence of extremely safe products and the generous amount of detergent.
IN2085
™.. makes science teaching easier.
083io?
• The cylinder will get hot, so let it cool before handling.
• This demonstration can be easily and safely scaled up for larger audiences. A 500-mL or 1-L Pyrex® graduated cylinder works
well in this case. You may have heard of this demonstration also referred to as elephant toothpaste.
• The slight brown tinge of the foam at the beginning is due to the presence of free iodine produced by the extreme oxidizing
ability of the 30% hydrogen peroxide.
• Another catalyst that will catalyze this reaction is manganese (IV) oxide, MnOr
• To demonstrate that oxygen is indeed one of the products, light a match and blow it out. Ideally, the center of the match will
still be orange. Hold the match very close to the foam produced — the match should reignite.
Discussion
This demonstration evolves a good deal of heat as shown by the steam coming off of the foam as it is produced. The reaction,
therefore, is exothermic. The action of a catalyst is demonstrated. The catalyst is the I-(aq) ion which speeds up the decomposition of the
hydrogen peroxide. The decomposition of hydrogen peroxide produces steam and oxygen gas. The oxygen gas and water vapor cause
the dishwashing liquid to foam.
2H202(aq)-->2H2O(g) + O2(g) + Energy
Connecting to the National Standards
This laboratory activity relates to the following National Science Education Standards (1996):
Unifying Concepts and Processes: Grades K-12
Evidence, models, and explanation
Content Standards: Grades 5-8
Content Standard B: Physical Science, properties and changes of properties in matter Content
Standards: Grades 9-12
Content Standard B: Physical Science, structure and properties of matter, chemical reactions, interactions of energy and matter
Answers to Worksheet Questions
1. Describe what happened in this demonstration.
Hydrogen peroxide and dishwashing solution were added to a 100-mL graduated cylinder. A small amount of sodium iodide
was added, which caused thick foam to erupt from the cylinder.
2. Write the chemical equation for the decomposition of hydrogen peroxide.
2H202(aq) -> 2H2O(g) + O2(g)
3. Why does the dishwashing solution foam?
The water vapor and oxygen gas get trapped in the dishwashing liquid, causing it to foam.
4. What was the purpose of the sodium iodide? Was it consumed during the reaction?
The sodium iodide served as a catalyst, which is a substance that speeds up a reaction but is not consumed during the
reaction. It was not consumed during the reaction.
Acknowledgement
Special thanks to Jim and Julie Ealy of The Peddie School in Hightstown, NJ.
Reference
Stone, C. H. J. Chem. Ed. 1944, 21, 300.
Materials for Old Foamey — Chemical Demonstration Kit are available from Flinn Scientific, Inc.
Catalog No.
Description
AP2085
Old Foamey — Chemical Demonstration Kit
Consult your Flinn Scientific Catalog/Reference Manual for current prices.
-2© 2007 Flinn Scientific, Inc. All Rights Reserved.
IN2085