eLearning
2009
Publication No. 91236
The Sodium Spectrum
Acid–Base Indicators
Introduction
No chemistry class is complete without the spectacular demonstration of alkali metals reacting with water. The Sodium
Spectrum is a novel variation that is much safer to perform than the standard sodium demonstration of simply dropping a small
piece of alkali metal into a beaker of water. It also demonstrates the colorful spectrum of colors possible with acid–base indicators.
Concepts
• Alkali metals—reaction with water
• Density
• Acid–base indicators
Materials
Sodium metal, Na, 5 small pieces
Mineral oil, 1000 mL
Phenolphthalein, 0.5% solution, 1 mL
Thymolphthalein, 0.5% solution, 1 mL
m-Nitrophenol, 1.0% solution, 1 mL
Water, 1000 mL
Glass cylinders, approximately 500-mL, 5
Ring stands and clamps (optional), 5
Safety Precautions
Sodium metal is a flammable, corrosive solid; dangerous when exposed to heat or flame; dangerous by reaction with moist air,
water, or any oxidizer. Purchasing pre-cut pieces for performing this demo greatly reduces the potential hazard of the material.
Sodium reacts with water to produce flammable hydrogen gas and a solution of corrosive sodium hydroxide. Wear chemical splash
goggles, chemical-resistant gloves, and a chemical-resistant apron. Please review your current Material Safety Data Sheets for
additional safety, handling, and disposal information.
Preparation
1.
2.
3.
4.
5.
6.
7.
8.
Clamp a hydrometer cylinder or large graduated cylinder to a ring stand for support (optional).
Add about 200 mL of water to each cylinder.
Add 8 drops of phenolphthalein and 2 drops of m-nitrophenol to the first cylinder (red).
Add 10–15 drops of m-nitrophenol to the second cylinder (yellow).
Add 2 drops of thymolphthalein and 12 drops of m-nitrophenol to the third cylinder (green).
Add 10 drops of thymolphthalein to the fourth cylinder (blue).
Add 8 drops of phenolphthalein and 2 drops of thymolphthalein to the fifth cylinder (violet).
Add 200 mL of mineral oil to each cylinder to form a layer above the water.
Procedure
1. Drop a piece of sodium, about the size of a small kernel of corn, into each cylinder and observe the reaction.
2. Wait about 2–3 minutes for all five indicator colors to fully develop as the aqueous solutions become basic.
Disposal
Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures governing the disposal of laboratory waste. Do not dispose of anything until the sodium has completely reacted. The mineral oil can
be stored and reused for future demonstrations and labs. The aqueous solution can be flushed down the drain with excess water
according to Flinn Suggested Disposal Method #26b.
Flinn Scientific—Teaching Chemistry eLearning Video Series
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Tips
• This is a very safe method for demonstrating the reactivity of sodium metal with water. Do not attempt this demonstration
with potassium.
• Make sure all the cylinders are stable and secure so they cannot tip over. Glass 500-mL graduated cylinders or large
hydrometer cylinders work very well.
• This demonstration works well with very small pieces of sodium. Flinn sells a bottle with 5 small pieces of sodium metal
that can actually be cut in half for this demonstration.
• Make sure the mineral oil is dry. If it is wet, the sodium may react more violently and form a less dense piece that will
float on top of the mineral oil layer.
Discussion
When added to the cylinder, sodium will sink until it reaches the interface between the two layers, at which time it reacts with
water, forming hydrogen gas and the base, NaOH:
2Na(s) + 2H2O(l) → H2(g) + 2NaOH(aq)
The evolution of hydrogen gas is evident, and hydrogen bubbles adhering to the sodium will carry it into the hydrocarbon
layer, temporarily stopping the reaction. The amount of hydrogen and heat evolved is kept under control by this swimming behavior, making this demonstration quite safe. The piece of sodium repeatedly dives down to the water-hydrocarbon interface, reacts,
then “swims” back up into the hydrocarbon layer until the reaction is complete. During the reaction, the piece of sodium is largely
devoid of corrosion, allowing the students to view its gray, metallic appearance.
Density is an important physical property that can be used to separate materials or control reactions. Sodium has a density of
0.97 g/mL and sits at the interface of water and a hydrocarbon. The interface between two immiscible solvents is an effective site
for controlling chemical reactions. Many industrial processes use this concept to react aqueous salts with nonpolar hydrocarbons.
Connecting to the National Standards
This laboratory activity relates to the following National Science Education Standards (1996):
Unifying Concepts and Processes: Grades K–12
Constancy, change, and measurement
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 of atoms, structure and properties of matter, chemical reactions
Acknowledgment
Special thanks to John Little, St. Mary’s High School, Stockton, CA, for bringing this demonstration to our attention.
Flinn Scientific—Teaching Chemistry™ eLearning Video Series
A video of the The Sodium Spectrum activity, presented by John Little, is available in Acid-Base Indicators, part of the Flinn
Scientific—Teaching Chemistry eLearning Video Series.
Materials for The Sodium Spectrum are available from Flinn Scientific, Inc.
Catalog No.
S0329
M0064
P0115
AP8599
N0088
T0073
Description
Sodium, Bottle of 5 Small Pieces for Demonstration
Mineral Oil, Light, 500 mL
Phenolphthalein Indicator Solution, 0.5%, 100 mL
Hydrometer Cylinder, 600-mL
meta-Nitrophenol, 25 g
Thymolphthalein, 5 g
Consult your Flinn Scientific Catalog/Reference Manual for current prices.
–2–
© 2009 Flinn Scientific, Inc. All Rights Reserved.
91236
eLearning
2009
Publication No. 91544
Orange Juice and Strawberry Float
Acid–Base Indicators
Introduction
It’s big, it’s colorful, it’s messy, and it’s chemistry! Watch as the “orange juice” in a beaker changes into a foamy “strawberry
float.” What a great way to introduce the properties of acid–base indicators to your students!
Concepts
• Acids and bases
• Acid–base indicators
Materials
Alconox® soap, 50 g
Water, tap
Methyl orange, 0.2% solution, 100 mL
Beakers, 2-L and 600-mL
Hydrochloric acid, HCl, 3 M, 270–280 mL
Demonstration tray, dishpan or aquarium
Sodium bicarbonate, NaHCO3, 50 g
Stirring rod, long
Safety Precautions
Hydrochloric acid is moderately toxic by ingestion and inhalation; it is corrosive to all body tissues, especially to the eyes.
Methyl orange solution is slightly toxic by ingestion. Alconox® and sodium bicarbonate are skin irritants. Avoid contact of all
chemicals with eyes and skin. This demonstration rapidly generates a foamy mixture which may spray in all directions. Wear chemical splash goggles, chemical-resistant gloves, and a chemical-resistant apron. Wash hands thoroughly with soap and water after
performing this demonstration. Please review current Material Safety Data Sheets for additional safety, handling, and disposal
information.
Procedure
1. Place a large demonstration tray or dishpan on the demonstration table.
2. Add approximately 300 mL of tap water to a 2-L beaker.
3. Add 50 g sodium bicarbonate and 50 g Alconox® to the 2-L beaker. Stir the solution with the long stirring rod. All of the
solid may not dissolve.
4. Add 100 mL of 0.2% solution methyl orange indicator to the beaker containing the sodium bicarbonate and Alconox®. Stir.
The resulting solution should look somewhat like orange juice; however, the orange solution is thicker and darker in color
than actual orange juice.
5. Pour approximately 270–280 mL of 3 M hydrochloric acid into a 600-mL beaker.
6. Place the beaker containing the sodium bicarbonate mixture in the center of the large demonstration tray or dishpan.
7. Quickly but carefully add the 270–280 mL of HCl, all in one pour, to the large, 2-L beaker. Stand back as the mixture will
immediately erupt out of the beaker.
8. Note the color change of the mixture. The solution will look like a strawberry float, but after some time, parts of the solution will turn yellow.
Flinn Scientific—Teaching Chemistry eLearning Video Series
91544
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Disposal
Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures governing the disposal of laboratory waste. The resulting mixture should be diluted with water, neutralized, and flushed down the drain
with plenty of water according to Flinn Suggested Disposal Method #24b.
Tips
• Prepare 0.2% methyl orange solution by dissolving 0.2 g of the solid indicator in 100 mL of water.
• This demonstration is very messy and produces over 13 liters of soap bubbles that may still contain small amounts of
hydrochloric acid. Please practice this demonstration before performing it in front of your students. All persons watching
the demonstration should be wearing chemical splash goggles. All amounts can be cut in half for a safer and less messy
(although less dramatic) alternative.
• This demonstration can also be performed in a 1-L or 3-L beaker. It is advised not to use an Erlenmeyer flask or a graduated cylinder as excessive splattering will erupt out of the narrow mouth.
• It is possible to substitute 75 g or 25 g of Alconox® (rather than 50 g) for more or less foam, respectively. Liquid dish
detergent also works (about three healthy squirts) but gives a lower quality foam. A less foamy reaction will occur using
25 g of sodium bicarbonate (rather than 50 g) and 1 M hydrochloric acid (rather than 3 M) with the same amount of soap
(50 g).
Discussion
The sodium bicarbonate reacts with the hydrochloric acid in a neutralization reaction to produce sodium chloride, water and
carbon dioxide gas according to the following equation:
NaHCO3(aq) + HCl(aq) → NaCl(aq) + H2O(l) + CO2(g)
Methyl orange is an acid–base indicator that is red at pH values less than 3.0, yellow-orange at pH > 4.4, and intermediate peach
colors in the pH range 3.0–4.4. The initial basic solution has a deep yellow-orange color. The color intensity of the initial solution
is due to the high indicator concentration. Upon adding the acid, the pH drops and a strawberry red color is observed. One of the
products of this neutralization reaction is carbon dioxide gas, which is rapidly produced and becomes trapped in the soap bubbles.
Over 13 liters of CO2 gas are produced in the reaction, resulting in an abundance of soap bubbles.
Connecting to the National Standards
This laboratory activity relates to the following National Science Education Standards (1996):
Unifying Concepts and Processes: Grades K–12
Constancy, change, and measurement
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
Answers to Worksheet Discussion Questions
1. Describe what happened in this demonstration. Make sure to mention all the chemicals used.
Hydrochloric acid was added to a large beaker containing a mixture of sodium bicarbonate, soap, and methyl orange, an
acid–base indicator. The solution, which was originally the color of orange juice, turned red and a great deal of foaming
was produced.
2. Write a chemical equation for the reaction that occurred when hydrochloric acid was added to the mixture inside the large
beaker.
NaHCO3(aq) + HCl(aq) → NaCl(aq) + H2O(l) + CO2(g)
–2–
© 2009 Flinn Scientific, Inc. All Rights Reserved.
91544
3. What product of this reaction and what chemical present in the original mixture were responsible for the foaming?
Explain.
The carbon dioxide gas (CO2) produced by the reaction between the hydrochloric acid and sodium bicarbonate, along
with the soap, were responsible for the foaming. The CO2 became trapped in the soap bubbles from the detergent, causing
an abundance of foamy bubbles.
4. What chemical was responsible for the color change? Explain.
The methyl orange indicator was responsible for the color change. Methyl orange is red in an acid and yellow-orange in a
base, and thus when the hydrochloric acid was added, the color of the solution changed to a strawberry red.
Flinn Scientific—Teaching Chemistry™ eLearning Video Series
A video of the Orange Juice and Strawberry Float activity, presented by Irene Cesa, is available in Acid–Base Indicators and
in Classroom Fun, part of the Flinn Scientific—Teaching Chemistry eLearning Video Series.
Materials for Orange Juice and Strawberry Float are available from Flinn Scientific, Inc.
Materials required to perform this activity are available in the Orange Juice to Strawberry Float—Chemical Demonstration
Kit available from Flinn Scientific. Materials may also be purchased separately.
Catalog No.
AP4778
A0126
H0034
M0076
S0042
AP5429
Description
Orange Juice to Strawberry Float—Chemical Demonstration Kit
Alconox, 4 lb
Hydrochloric Acid, 3 M, 500 mL
Methyl Orange, 25 g
Sodium Bicarbonate, 500 g
Demonstration Tray
Consult your Flinn Scientific Catalog/Reference Manual for current prices.
–3–
© 2009 Flinn Scientific, Inc. All Rights Reserved.
91544
Orange Juice and Strawberry Float Worksheet
Discussion Questions
1. Describe what happened in this demonstration. Make sure to mention all the chemicals used.
2. Write a chemical equation for the reaction that occurred when hydrochloric acid was added to the mixture inside the large
beaker.
3. What product of this reaction and what chemical present in the original mixture were responsible for the foaming?
Explain.
4. What chemical was responsible for the color change? Explain.
91544
© 2009 Flinn Scientific, Inc. All Rights Reserved. Reproduction permission is granted only to science teachers who have purchased Acid–Base Indicators in the Flinn Scientific—Teaching
Chemistry™ eLearning Video Series. No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and retrieval system, without permission in writing from Flinn Scientific, Inc.
eLearning
2009
Publication No. 95017
Sudsy Kinetics
Introduction to Reaction Rates
Introduction
Teach kinetics concepts in a fun and sudsy way! This demonstration provides an interesting twist on the traditional “Old
Foamey” or “Elephant Toothpaste” reaction. Not only will your students be amazed at the sudsy eruption—they will learn kinetics
concepts along the way!
Concepts
• Kinetics
• Decomposition reaction
• Reaction intermediates
• Catalyst
Materials Needed
Chemicals
Hydrogen peroxide, H2O2, 30%, 20 mL
Alconox® detergent, 3–4 g
Hydrogen peroxide, H2O2, 10%, 20 mL
Sodium iodide solution, NaI, 2 M, 4–5 mL*
Hydrogen peroxide, H2O2, 3%, 20 mL
Tap water
Equipment
Graduated cylinders, 10-mL, 3
Large, plastic demonstration tray
Graduated cylinders, 100-mL, 3
Lighter or matches
Graduated cylinders, 500-mL, 2
or Erlenmeyer flasks, 500-mL, 2
Spoon or scoop
Wood splint
Safety Precautions
Hydrogen peroxide solution, 30%, is severely corrosive to the skin, eyes, and respiratory tract and is a very strong oxidant.
It is a dangerous fire and explosion risk. Do not heat 30% hydrogen peroxide. Sodium iodide is slightly toxic by ingestion. The
decomposition reaction of 30% hydrogen peroxide is highly exothermic. Use only borosilicate glass graduated cylinders. Steam
and oxygen are produced very quickly—do not stand over the reaction flask. Wear chemical splash goggles, chemical-resistant
gloves, and a chemical-resistant apron. Avoid contact of all chemicals with eyes and skin. Wash hands thoroughly with soap and
water before leaving the laboratory. Please review current Material Safety Data Sheets for additional safety, handling, and disposal information.
Procedure
Part 1. Effect of Concentration on the Rate of the Reaction
1. Place three 100-mL graduated cylinders in a large, plastic demonstration tray or dishpan.
2. Add 20 mL of 30% hydrogen peroxide to the first cylinder, 20 mL of 10% hydrogen peroxide to the second cylinder, and
20 mL of 3% hydrogen peroxide to the third cylinder.
3. Add 1 small scoop (3–4 g) of solid Alconox® detergent to each cylinder and swirl to mix the detergent.
4. Measure out 5 mL of 2 M sodium iodide solution into each of three 10-mL graduated cylinders. Ask your students to predict the relative rate at which each hydrogen peroxide solution will react with potassium iodide.
Flinn Scientific—Teaching Chemistry eLearning Video Series
95017
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5. Ask for three student volunteers. Make sure the students are wearing chemical splash goggles; warn them to step back as
soon as they pour. Have the students simultaneously pour sodium iodide solution into the three individual cylinders containing differing concentrations of hydrogen peroxide. Make observations. White foam erupts from the cylinder with the
30% hydrogen peroxide the fastest, the 10% hydrogen peroxide next, and only slowly rises up from the cylinder containing
3% hydrogen peroxide.
Part 2. Old Foamey—Observing a Reaction Intermediate and Products
1. Place a 500-mL graduated cylinder on a large, plastic demonstration tray.
2. Measure out 20 mL of 30% hydrogen peroxide and add it to the cylinder.
3. Add 1 small scoop (3–4 g) of solid Alconox® detergent to the cylinder and swirl the mixture to dissolve the detergent.
4. Measure out 5 mL of 2 M sodium iodide solution and, quickly but carefully, pour this into the cylinder. In a few seconds,
copious amounts of white foam will be produced. Observe closely at the beginning of the reaction. A brown foam is produced at first but then turns white before it erupts out of the cylinder. This is due to the presence of the free iodine produced by the oxidation of iodide ions by hydrogen peroxide.
5. Notice the steam coming off from the foam—this indicates that the decomposition reaction is very exothermic.
6. Light a wood splint and blow out the flame. Insert the glowing wood splint into the foam. The wood splint will re-ignite in
the foam—this indicates that the gas in the foam is pure oxygen. Take the glowing splint out of the foam, re-insert it, and
watch it re-ignite again. This can be repeated numerous times.
Part 3. Comparing the Rate of the Reaction with its Stoichiometry
Purpose: In this part, the total number of moles of peroxide is the same in each container, although one has been diluted with
water. An equal volume of foam is produced by both but at different rates, with the more concentrated one reacting faster. The
more dilute one will eventually produce an equal amount of product. This demonstrates that the rate at which the product is produced is not necessarily related to the amount of product.
1. Carefully measure out 15 mL of 30% hydrogen peroxide and add it to a 500-mL graduated cylinder or Erlenmeyer flask.
2. Carefully measure out a second 15 mL portion of 30% hydrogen peroxide and add it to a different 500-mL graduated cylinder or Erlenmeyer flask. To this second cylinder or flask, also add 30 mL of tap water.
3. Add a scoop (3–4 g) of Alconox® detergent to each cylinder or flask. Swirl to dissolve the detergent.
4. Place both containers in the center of a large, plastic demonstration tray.
5. Ask for two student volunteers. Again make sure they are wearing goggles and are warned to step back. Have them add
4 mL of 2 M sodium iodide solution to the two individual cylinders. The reaction will turn brown immediately and white
foam will rise up out of each cylinder, with the more concentrated mixture rising more rapidly. However, keep observing! Compare the final volume of foam produced by each reaction. The diluted peroxide will eventually produce the same
amount of foam since an equal number of moles of hydrogen peroxide were used in each reaction.
Disposal
Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures governing the disposal of laboratory waste. The foam and any solution left in the cylinder or on the plastic tray may be rinsed down the
drain with excess water according to Flinn Suggested Disposal Method #26b.
Tips
• Each part of the demonstration is designed to teach a different concept in chemistry. First perform Part 1 with the three
concentrations of peroxide, discussing how rate is dependent on concentration. Ask students which one they would like to
see again—they will surely choose the 30% one. Then perform Part 2 in a larger graduated cylinder, this time discussing
the reactions that are occurring, the brown iodine intermediate, production of heat, and the formation of water and oxygen
gas. Finally perform Part 3 in flasks. Discuss the stoichiometry of the decomposition reaction and use the ideal gas law
(PV = nRT) to calculate the volume of gas that should be produced.
• The decomposition reaction is exothermic and the cylinder will become very hot. Be sure to let it cool before handling.
–2–
© 2009 Flinn Scientific, Inc. All Rights Reserved.
95017
• If a demonstration tray is not available, use a dishpan or perform this demonstration in a laboratory sink.
• The safe products of this reaction, as well as the generous amount of detergent, make cleanup very easy.
Discussion
Hydrogen peroxide decomposes to produce oxygen and water according to the following overall equation.
2H2O2(aq) → 2H2O(l) + O2(g) + Energy
The reaction is quite slow unless catalyzed by a substance such as iodide ions, manganese metal, manganese dioxide, iron(III) ions,
and many other substances such as yeast or even blood. A catalyst is a substance that, when added to a reaction mixture, participates
in the reaction and speeds it up, but is not itself consumed in the reaction. The iodide ion is used as a catalyst in this demonstration.
While the complete mechanism is not known, the observations of this reaction are consistent with the following reactions.
Step 1: Hydrogen peroxide and iodide mix to cause spontaneous formation of the brown color from the I3– intermediate with
very little foam. This reaction shows that the catalyst is involved in the reaction.
H2O2(aq) + 3I–(aq) → 2OH–(aq) + I3–(aq)
ΔHrxn = –37.0 kcal
ΔGrxn = –18.5 kcal
Step 2: The intermediates then combine with additional hydrogen peroxide to cause the spontaneous disappearance of the
brown color and the production of copious amounts of foam containing oxygen gas. The I– is regenerated in the reaction, showing
that the catalyst is not consumed in the reaction.
H2O2(aq) + I3–(aq) + 2OH–(aq) → 2H2O(l) + 3I–(aq) + O2(g)
ΔHrxn = –8.3 kcal
ΔGrxn = –30.8 kcal
Overall Reaction: Combining Steps 1 and 2 gives the overall reaction shown below. Notice that the enthalpy or heat of reaction (ΔHrxn) is negative, indicating that the reaction is exothermic and releases heat. The free energy of the reaction (ΔGrxn), which
takes into account not only the enthalpy but also the entropy of the reaction, is also a negative value, indicating that the reaction
takes place spontaneously. If the reaction occurs spontaneously, then why is a catalyst needed? The iodide catalyst causes the reaction to occur at a reasonable rate—without it, the reaction would occur, but so slowly that it would not be observable.
2H2O2(aq) → 2H2O(l) + O2(g) + Energy
ΔHrxn = –45.3 kcal
ΔGrxn = –49.3 kcal
Why all the foam? A sample calculation is given below for the volume of oxygen released by the decomposition of 15 mL (as
in Part 3) of 30% hydrogen peroxide. Hydrogen peroxide solution (30%) has a specific gravity of 1.11 g/mL. Therefore, the mass
of solution can be determined
1.11 g/mL × 15 mL = 16.7 g of solution
Since only 30% of the total volume of solution is H2O2, then
30% of 16.7 g of solution = 5.01 g of H2O2
Since the molecular weight of H2O2 is 34.02 g/mol, the number of moles of H2O2 is
5.01 g × 1 mole/34.02 g = 0.147 mol of H2O2 used
From the balanced equation, there is a 2 to 1 ratio of hydrogen peroxide to oxygen gas. Thus, the number of moles of O2 released
can be determined
0.147 mol H2O2 × 1 mole O2/2 mol H2O2 = 0.0736 mol O2
This shows that the reaction should produce 0.0736 moles of oxygen gas. To determine the volume of this amount of gas, use the
ideal gas law, PV = nRT, assuming a reaction temperature of the steaming foam of approximately 100 °C (or 373 K) and standard
pressure (1 atm). Solving for volume, V = nRT/P, where n = 0.0736 mol, R = ideal gas constant = 0.0821 Latm/molK, T = 373 K
and P = 1 atm, the volume of oxygen gas can be calculated
V = (0.0736 mol) (0.0821 Latm/molK) (373 K)/1 atm = 2.25 L O2.
The volume of oxygen expected, then, is 2.25 liters.
–3–
© 2009 Flinn Scientific, Inc. All Rights Reserved.
95017
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
Flinn Scientific—Teaching Chemistry™ eLearning Video Series
A video of the Sudsy Kinetics activity, presented by Irene Cesa, is available in Introduction to Reaction Rates, part of the
Flinn Scientific—Teaching Chemistry eLearning Video Series.
Materials for Sudsy Kinetics are available from Flinn Scientific, Inc.
Materials required to perform this activity are available in the Sudsy Kinetics—Chemical Demonstration Kit available from
Flinn Scientific. Materials may also be purchased separately.
Catalog No.
AP4866
AP5429
H0008
H0009
S0084
A0126
GP2020
GP2030
Description
Sudsy Kinetics—Chemical Demonstration Kit
Demonstration Tray
Hydrogen Peroxide, 30% Reagent, 500 mL
Hydrogen Peroxide, 3%, Lab Grade, 500 mL
Sodium Iodide, Reagent, 100 g
Alconox® Detergent, 4 lb Carton
Graduated Cylinder, Borosilicate Glass, 100 mL
Graduated Cylinder, Borosilicate Glass, 500 mL
Consult your Flinn Scientific Catalog/Reference Manual for current prices.
–4–
© 2009 Flinn Scientific, Inc. All Rights Reserved.
95017
Catalog No. AP5943
Publication No. 5943
Whoosh Bottle
Chemical Demonstration Kit
Introduction
Wow your students with a whoosh! Students will love to see the blue alcohol flame shoot out the mouth of the bottle and
watch the dancing flames pulsate in the jug as more air is drawn in.
Concepts
• Exothermic reactions
• Activation energy
• Combustion
Background
Low-boiling alcohols vaporize readily, and when alcohol is placed in a 5-gallon, small-mouthed jug, it forms a volatile mixture with the air. A simple match held by the mouth of the jug provides the activation energy needed for the combustion of the
alcohol/air mixture.
Only a small amount of alcohol is used and it quickly vaporizes to a heavier-than-air vapor. The alcohol vapor and air are all
that remain in the bottle. Alcohol molecules in the vapor phase are farther apart than in the liquid phase and present far more surface area for reaction; therefore the combustion reaction that occurs is very fast.
Since the burning is so rapid and occurs in the confined space of a 5-gallon jug with a small neck, the sound produced is very
interesting, sounding like a “whoosh.” The equation for the combustion reaction of isopropyl alcohol is as follows, where 1 mole
of isopropyl alcohol combines with 4.5 moles of oxygen to produce 3 moles of carbon dioxide and 4 moles of water:
(CH3)2CHOH(g) + 9⁄2O2(g)
→ 3CO2(g) + 4H2O(g)
ΔH = –1,235 kJ/mol
Materials (for each demonstration)
Whoosh bottle, plastic jug, 5-gallon*
Funnel, small
Isopropyl alcohol, (CH3)2CHOH, 20–30 mL*
Graduated cylinder, 25-mL
Match or wood splint taped to meter stick
Fire blanket (highly recommended)
*Materials included in kit.
Safety shield (highly recommended)
Safety Precautions
Please read all safety precautions before proceeding with this demonstration.
• Isopropyl alcohol is a flammable liquid and a fire hazard. It is slightly toxic by ingestion and inhalation. Use in a wellventilated room.
• Always recap the alcohol bottle and move it far from the demonstration area. Never leave an open bottle of alcohol in the
vicinity of the demonstration.
• A safety shield is highly recommended for explosions. Even the mildest explosion creates some chance of shattering and
flying objects. Protective eyewear must be worn by the demonstrator as well as by anyone viewing the demo.
• Never perform alcohol explosions in glass bottles. The large quantities of gases (H2O and CO2) produced during the rapid
combustion will easily shatter a glass container. Serious accidents have occurred performing this demonstration in a glass
container—do not use glass. Use the plastic jug that is provided in this kit.
CHEM-FAX姠. . .makes science teaching easier.
IN5943
111910
• Always pour out excess unvolatilized liquid alcohol from the plastic jug before igniting. If any liquid alcohol is left, it will
increase the amount of gaseous afterburning. The liquid could also ignite, which may cause the plastic jug to melt. Always
keep a lid or some sort of cover handy, which can be placed over the mouth of the jug to extinguish the flame if it continues so long as to begin melting the plastic. Excess alcohol on the outside of the jug should be wiped off in order to avoid
its igniting and softening the plastic jug.
• Never, ever use a pure oxygen environment as the potential for an extremely violent and deadly explosion is possible.
• Never use methyl alcohol for this demonstration. The high volatility of methyl alcohol means that it has the potential for
the most violent combustion of any alcohol.
• Replace the plastic “whoosh bottle” should it show grazing, frosting, cracking, or any small flaws. Routinely replace the
bottle after approximately 20 uses or so.
• Do not perform this demonstration directly underneath smoke/heat detectors or sprinkler systems.
• Make sure the ceiling is at least 4 feet above the whoosh bottle to prevent possible scorching and fire.
• Always wear protective eyewear when performing this demonstration. Please consult current Material Safety Data Sheets
for additional safety information on isopropyl alcohol.
Preparation
Before each demonstration, inspect the plastic whoosh bottle for grazing, frosting, cracking, or any small flaws. Replace the
bottle if it shows signs of fatigue.
Procedure
1. Add about 20–30 mL of isopropyl alcohol to the 5-gallon plastic jug. Do not add more than 30 mL of alcohol. Recap the
bottle of alcohol tightly and move it far from the demonstration area.
2. Lay the jug sideways on a flat surface allowing the alcohol to flow from base to mouth. Slowly swirl the jug for about 30
seconds, trying to spread alcohol liquid completely over the entire interior surface. This allows the liquid alcohol to volatilize and makes the vapor concentration uniform throughout the bottle. If a lot of liquid alcohol is still visible, swirl the
bottle for another 30 seconds.
3. Pour out any excess liquid alcohol and shake out the bottle. Wipe the inside and outside neck of the bottle to remove any
remaining liquid.
4. Stand the jug on the floor, placing it in the front of the room and behind a safety shield. Note: If desired, the demonstration
can be performed on a fireproof demonstration table provided that the ceilings are at least 10 feet high.
5. Dim the lights in the room.
6. Light a match or wood splint that is taped to a meter stick or other long stick.
7. Stand back and, at arm’s length, bring the burning match or wood splint over or slightly down into the mouth of the bottle.
Note: Be sure you are on the safe side of the safety shield as well.
8. Observe the explosive “whoosh” that results.
9. After the reaction has subsided and all the flames are out, wait for a minute or two until the bottle has cooled slightly. Pour
out the water droplets from the bottle into a 25-mL graduated cylinder using a small funnel. As much as 12–14 mL of
water may result, showing that water is one of the products of the combustion of alcohol.
Repeating the Demonstration
The demonstration cannot be repeated immediately for a few reasons—for one, the demonstration will not work due to the
buildup of CO2 in the bottle. There is not enough oxygen in the bottle to allow combustion to occur. More importantly, it can be
extremely dangerous to add alcohol to the jug if the jug is still hot. A flash back can occur causing a fire.
Therefore, in order to successfully repeat the demonstration for the same class or another class, follow the steps below:
1. Allow the bottle to cool to room temperature.
2. Pour out the water that forms as a result of the combustion.
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© 2010 Flinn Scientific, Inc. All Rights Reserved.
IN5943
3. Fill the bottle with about 1⬙ of cold tap water and swirl the tap water around in the bottle. Pour the tap water into the sink,
and repeat the washing with more cold tap water. Pour all the water out into the sink.
4. Dry out the bottle as much as possible by either allowing it to sit upside down or (to speed up the drying) by drying it with
a long string of paper towels pushed into the mouth. A few water droplets on the inside of the bottle do not seem to hinder
the combustion.
5. In order to reduce the amount of water in the bottle and speed up the drying, try a double rinse of the bottle with a small
amount of isopropyl alcohol.
6. Follow the procedure steps 1–9 above.
Disposal
Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures governing the disposal of laboratory waste. Excess alcohol may be disposed of by allowing it to evaporate in a fume hood according to
Flinn Suggested Disposal Method #18a. Before storing the jug, allow it to remain open to the air to allow any remaining vapors to
be released.
Observable Effects
The first effect that may be observed is the usual “whoosh,” which involves a moderately violent thrust of flames and blue gas
out of the mouth of the bottle. Some afterburning or dancing flames of burning vapor in the body of the bottle may also result.
The second effect is a slower burn of gas down the inside surface of the bottle, producing a ring, plate, or cone of fire, which
may be accompanied by an upward thrust or ball of yellow flames in the center of the jug. The sound accompanying these slower
burns is actually more of a “whomp.” This effect can also be observed by using 70% isopropyl alcohol, illustrating reduced vapor
pressure due to dilution.
Tips
• Enough isopropyl alcohol (250 mL) is provided to perform this demonstration at least eight times. Various sound and
flame effects may be produced depending on the alcohol used and its dilution with water. Try using ethyl alcohol or n-propyl alcohol. Compare the results to isopropyl alcohol. Ethyl alcohol proceeds somewhat faster and more violently due to
its higher volatility. Propyl alcohol burns slower producing more heat, which may damage the bottle. Do not try this demonstration with methyl alcohol. The high volatility of methyl alcohol means that one must be particularly cautious when
using methyl alcohol as it has the potential for the most violent combustion and possible rupture of the bottle.
• Depending on how much alcohol vapor is in the bottle, you may have to place the flame slightly inside the lip of the
whoosh bottle before it ignites.
• The demonstration works best if the alcohol vapor is prepared immediately before the demonstration. If the bottle with the
vapor sits for a while, the vapor tends to settle and is harder to light.
• Reagent isopropyl alcohol (99%) or 70% isopropyl alcohol can be used for the demonstration. The 70% alcohol produces
a slightly slower burn due to the water vapor.
• Use a graduated cylinder to measure the volume of water produced by the reaction. Have your students perform calculations to determine the volume of water expected from the starting amount of isopropyl alcohol.
For example, if 20 mL of isopropyl alcohol (density = 0.78 g/mL) are used:
20 mL × 0.78 g/mL = 15.6 g × 1 mole/60 g = 0.26 mol isopropyl alcohol
From the balanced equation,
0.26 mol isopropyl alcohol × 4 mol H2O/1 mol isopropyl alcohol = 1.04 mol H2O
So,
1.04 mol H2O × 18 g/mol = 18.7 g = 18.7 mL of H2O expected
Discuss possible reasons why the actual volume of water may have been slightly less, such as evaporation or the droplets
of water remaining on the inside of the bottle.
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© 2010 Flinn Scientific, Inc. All Rights Reserved.
IN5943
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, transfer of energy
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.
A small amount of isopropyl alcohol was used to coat the inside of a large plastic jug. A light wood splint was held over
the jug with a meter stick. The isopropyl alchol ignited, causing an explosive “whoosh” sound accompanied by flames
jumping out of the mouth of the jug. Some flames could be seen afterward in the bottle. Also, flames inside the jug thrust
upward and around, making a “whomp” sound.
2. Write a balanced chemical equation for the combustion of isopropyl alcohol.
(CH3)2CHOH(g) + 9/2O2(g) →
3CO2(g) + 4H2O (g)
3. Calculate the volume of water you would expect to be produced by this reaction if 20 mL of isopropyl alcohol with a density of 0.78 g/mL were used.
20 mL × 0.78 g/mL = 15.6 g × 1 mole/60 g = 0.26 mol isopropyl alcohol
From the balanced equation, we know that 1 mol isopropyl alcohol = 4 mol water.
Therefore, 0.26 mol isopropyl alcohol × 4 mol H2O/1 mol isopropyl alcohol = 1.04 mol H2O
1.04 mol H2O × 18 g/mol = 18.7 mL of H2O expected.
4. Why does this reaction occur faster when the alcohol is in the vapor phase rather than the liquid phase?
Alcohol molecules that are in the vapor phase combust faster than molecules in the liquid phase because they are spread
further apart in the container. They therefore have a much greater surface area for the reaction, and this increased surface
area allows for more molecules to react immediately with oxygen in the air.
Acknowledgments
Flinn Scientific would like to thank John Fortman, Dept. of Chemistry, Wright State University, Dayton, OH for all of his
research in providing safety notes and variations on this excellent demonstration. John has written an excellent article on this demonstration; see reference listed below. Lee Marek, Naperville North H. S., Naperville, IL and Bill Deese have also popularized this
demonstration.
Reference
Fortman, J. J.; Rush, A. C.; Stamper, J. E. J. Chem. Ed. 1999, 76, 1092–1093.
Materials for Whoosh Bottle—Chemical Demonstration Kit are available from Flinn Scientific, Inc.
Catalog No.
AP5943
SE225
I0019
E0009
Description
Whoosh Bottle—Chemical Demonstration Kit
Safety shield, 30⬙ × 16⬙
Isopropyl alcohol, 500 mL
Ethyl alcohol, 500 mL
Consult your Flinn Scientific Catalog/Reference Manual for current prices.
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© 2010 Flinn Scientific, Inc. All Rights Reserved.
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Name: ___________________________________
Demonstration Worksheet
Discussion Questions
1. Describe what happened in this demonstration.
2. Write a balanced chemical equation for the combustion of isopropyl alcohol.
3. Calculate the volume of water you would expect to be produced by this reaction using the equation above. Remember,
20 mL of isopropyl alcohol with a density of 0.78 g/mL were used.
4. Why does this reaction occur faster when the alcohol is in the vapor phase rather than the liquid phase?
IN5943
© 2010 Flinn Scientific, Inc. All Rights Reserved. Reproduction permission is granted only to science teachers who have purchased Whoosh Bottle, Catalog No. AP5943, from Flinn Scientific, Inc.
No part of this material may be reproduced or transmitted in any form or by any means, electronic or mechanical, including, but not limited to photocopy, recording, or any information storage and
retrieval system, without permission in writing from Flinn Scientific, Inc.