The
Gas Reaction Catalyst Tube is sold by Educational Innovations. The
catalyst tube comes with a booklet of thirteen experiments and
classroom demonstrations that can be performed in class or laboratory.
Educational Innovations sells worldwide. Visit their website (Part
Number GAS-100 or keyword 'gas') You can also look through the book
that comes with the catalyst tube and read about the thirteen
experiments and various gas tests.
Part One. General Information
A. About the Catalyst
B. The Gas Reaction Catalyst Kit
C. Additional Equipment Required
D. Setting Up the Apparatus
E. Properly Heating the Catalyst Tube
F. Explosion Risk! Please Read!
G. Activating the catalyst
H. Sources of Gases
I. Toxicity
J. Clean-up and Storage
Part
Two. Reactions Using the Catalyst
A. Oxidation of Methane with Air.
B. Oxidation of Ethene with Air.
C. Oxidation of Carbon Monoxide with Air.
D. Hydrogenation of Ethene
E. Catalytic Oxidation of Ammonia.
F. Methane and Nitrogen Dioxide.
G. Carbon Monoxide and Nitrogen Dioxide.
H. Decomposition of Nitrous Oxide
I. Nitrous Oxide and Ammonia
J. Nitrous Oxide and Carbon Monoxide
K. Nitrous Oxide and Methane
L. Trying Other Catalytic Reactions
Part
Three. Confirmatory Tests
A. Acidity test.Part Four. Support
B. Ammmonia test
C. Bromine-water test.
D. Flammability test.
E. Gas chromatography.
F. Glowing Splint test
G. Limewater test
H. Water test
A. We repair and recycle!
B. Our Gas Chemistry Website
C. Microscale Gas Chemistry Book
D. Ordering syringes, parts, etc. from Educational Innovations

A.
About
the Catalyst
The gas reaction catalyst
tube that you have purchased consists of an extremely this coating of
palladium
atoms dispersed over a square tube shaped ceramic support. The
palladium
present is of almost negligible mass yet is the material that actually
catalyses the reactions described here. The catalyst and ceramic
support is housed in a 10-mm inside diameter tube (12-mm O.D.) made of
borosilicate glass. The net volume of the glass tube is about 7 -
8 mL.
B. The
Gas
Reaction Catalyst Kit (Reorder Part Number
GAS-100)
The gas reaction catalyst
kit contains:
• one catalyst tubeC. Additional Equipment Required
• two 60-mL syringes
• two latex LuerLOK syringe cap fittings
• one 17-cm length of latex connector tubing, 1/8-inch (3.175 mm) ID
• two plastic vial caps (used for generating various gases)
• this booklet
• a Bunsen burner
• two ring stands with one three-prong clamp each (optional)
• silicone oil lubricant
In addition, the various chemical tests
of the gaseous products require equipment and chemicals that are not
provided.
These are described in the tests later in these instructions.
D.
Setting
Up the Apparatus
The assembled apparatus
is shown in the Figure. Two short pieces (approx. 2-cm) of Latex
tubing connect the catalyst tube to the two syringes. The syringe
on the left contains the reagent gas mixture ready to be passed through
the catalyst. The plunger of the receiver syringe (right) must be
able to move freely in the syringe barrel because it should move
outward
on its own as the plunger of the reactant syringe is pushed
inward.
This is assured by lubricating the black rubber plunger diaphragm with
silicone oil. Useful hint: Pull the plunger of the receiver
syringe
slightly outward so that the rubber diaphragm is not resting on the
bottom
of the barrel — this allows the initial outward movement of the plunger
to commence at a lower positive pressure. Two ring stands and
clamps
hold the two syringes in the appropriate position above the burner's
flame.
The clamps should not hold the syringes tightly and must allow for free
rotation of the syringes and catalyst tube for even heating. With
some experience, we have found that it is easier to hold the syringes
with
one’s hands instead of using a ring stand.
E.
Properly
Heating the Catalyst Tube
Heat from a Bunsen burner
flame is capable of softening the glass portion of the catalyst
tube.
When the glass is soft, it is susceptible to deformations and even
"blow
holes" if the pressure inside the system is increased by moving the
plunger
of the syringe. To prevent overheating the glass, use only a cool
Bunsen burner flame. Minimize the amount of air used so that the
flame has a soft, ill-defined blue inner cone. Position the
catalyst
tube at least 1 cm above the tip of the inner cone. Watch for
traces
of red, orange or yellow in the flame above the catalyst tube.
These
colors indicate that the glass is softening. If this should
happen,
remove the flame and adjust the flame.
F.
Explosion
Risk! Please Read!
The oxidation reactions
involving hydrocarbons (methane and ethene) described herein utilize
air
as a source of oxygen. Do NOT attempt these catalysis reactions
using
oxygen instead of air! An explosion will result!
G.
Activating
the catalyst
The ceramic catalyst
will appear tan or brown until it is activated. "Activation"
simply
involves heating the catalyst tube in a cool flame until it turns dark,
sometimes even black. This takes less than a minute and can be
done
as part of the first experiment. Heat the catalyst tube evenly by
rotating the syringes periodically in the flame.
H.
Sources
of Gases.
The gas catalysis
experiments
described here require samples of various gases. Compressed
cylinders
of gases are convenient and the purity is assumed to be quite
good.
Natural gas can be used as a source of methane. All of the
reagent
gases in this article can be prepared by simple methods we have
described
in our series in Chem13 News over the past several years. These
gas
preparations are also available in our book, Microscale Gas Chemistry,
available from Educational Innovations and at our website (See Part
Four).
Gases prepared in this method contain small amounts of air.
I.
Toxicity.
Manipulating gases in syringes is generally safe
and unintentional discharges are not common. Nevertheless, such
discharges
are possible and it is important to read and understand the following
information.
Nitrogen dioxide has an irritating odor and is a poisonous gas.
Concentrations
of 100 ppm are dangerous. To put this in perspective, if the
contents
of one entire syringe of NO2 (60 mL) were discharged into a volume of 1
m3, the concentration of NO2 would be 60 ppm. Ammonia has a
pungent
irritating odor and is highly poisonous. Although less toxic than
ammonia and nitrogen dioxide, carbon monoxide is toxic but has no
odor.
Symptoms of carbon monoxide poisoning include headache, mental
dullness,
weakness, nausea and vomiting. Exercise caution when working with
poisonous gases and vacate areas that are contaminated with
unintentional
discharges of gas.
J.
Clean-up
and Storage
After reactions, heat the catalyst for 30
seconds in the flame, remove the flame and purge the catalyst with a
syringe
filled with an inert gas such as nitrogen or argon. Air may be
used
if inert gases are not available. Allow the catalyst to
cool.
Store the gas reaction catalyst tube in a sealed plastic bag.
Clean
syringes with soap and water. Be sure to remove all of the
lubricant
as that will deteriorate the plunger’s rubber seal. To improve
the
syringe’s lifetime, store the plunger out of the barrel.
A. Oxidation of Methane with Air.
CH4(g) + 2 O2(g)
CO2(g) + 2 H2O(g)
DH = -803 kJ
Fill the reagent syringe with 40 mL air (0.34 mmol O2) and 20 mL methane (0.82 mmol.) Connect the reagent syringe to the catalyst tube and assemble the apparatus as shown in the figure. Pass about 10 mL of gas mixture through the catalyst tube to (a) check for leaks, (b) determine that the plunger in the receiver flask moves freely; and (c) displace air (or previous gas mixtures) from the catalyst tube. (Option: Remove the receiver syringe from the catalyst tube, discharge the 10-mL air from the receiver syringe and reconnect to the catalyst tube.) Heat the catalyst tube evenly on all sides for a total of about 30 seconds. Slowly pass about half of the methane/air reagent gas mixture through the catalyst tube over the course of about 30 seconds. Be alert for problems — the volume of gases collected in the receiver syringe should equal the volume decrease in the reagent syringe. After half of the gas mixture has been passed through the catalyst tube, remove the heat. Remove both syringes and cap them with latex syringe caps. Label the syringes with a marker pen.
You may wish to
perform
one or more of the following tests, described in Part Three, on the
reagent
gas mixture and product gas mixture:
(a) Limewater test for CO2
(b) Flammability test
(c) Gas chromatography
(d) Water test
More information about this
experiment along with pictures can be found at our gas chemistry
website
for methane. See Experiment 11
at
this site.
B. Oxidation of Ethene with Air.
C2H4(g)
+ 3 O2(g)
2 CO2(g) + 2 H2O(g)
DH = -1323 kJ
Follow the general procedure described in Reaction 1 for methane. Use 50 mL air (0.43 mmol O2) and 10 mL ethene (0.41 mmol.)
You may wish to
perform
one or more of the following tests, described in Part Three, on the
reagent
gas mixture and product gas mixture:
(a) Lime water test for CO2C. Oxidation of Carbon Monoxide with Air.
(b) Flammability test
(c) Gas chromatography
(d) Bromine-water test
(e) Water test
2 CO(g) + O2(g)
2 CO2(g) DH
= -566 kJ
In this oxidation, either air or oxygen may be used as the oxidant. Follow the general procedure described above for methane. Use 45 mL air (0.38 mmol O2) and 15 mL carbon monoxide (0.6 mmol) or 40 mL CO (1.6 mmol) and 20 mL O2 (0.8 mmol).
You may wish to
perform
one or more of the following tests, described in Part Three, on the
reagent
gas mixture and product gas mixture:
(a) Lime water test for CO2D. Hydrogenation of Ethene
(b) Gas chromatography
(c) If O2 is used rather than air, the Flammability and Glowing Splint test may be performed.
C2H4(g)
+ H2(g)
C2H6(g)
DH
= -137 kJ
Fill the reagent
syringe with 30 mL ethene (1.2 mmol) and 30 mL hydrogen (1.2
mmol.)
Connect the reagent and receiver syringes to the catalyst tube as shown
in the Figure. Pass about 10 mL of gas mixture through the
catalyst
tube to purge it of air. Remove the receiver, discharge the air
and
then reconnect as quickly as possible in order to minimize
H2-loss.
Heat the catalyst tube evenly on all sides for about 30 seconds, then
slowly
pass about half of the C2H4/H2 reagent gas mixture through the catalyst
tube over the course of about 30 seconds. The volume of gases collected
in the receiver syringe should be less than the volume decrease in the
reagent syringe; 2 mol gaseous reactants become 1 mol of gaseous
products
if the reaction efficiency is 100%. In our experience, these
experimental
conditions cause hydrogenation with about 50% efficiency. Nearly
complete hydrogenation can be achieved by activating the catalyst tube
in a gentle flame with pure hydrogen (60 mL) prior to passing the
mixture
through the catalyst tube. After half of the gas mixture has been
passed through the catalyst tube, remove the heat. Remove both
syringes
and cap them with Latex syringe caps. Label the syringes.
The Bromine-water test for C2H4 should
confirm
that there is less ethene in the product syringe than in the reactant
syringe.
Gas chromatography allows for a quantitative estimation of the extent
of
hydrogenation. See Part Three for details.
E. Catalytic Oxidation of Ammonia.
4 NH3(g) + 3 O2(g)
2 N2(g) + 6 H2O(g) DH
= -1268 kJ
This reaction has been
the subject of numerous demonstrations involving glowing platinum or
copper
(See: (a) A Demo A Day, A Year of Chemical Demonstrations, Flinn
Scientific
1995; pp 224; (b) Shakhashiri, B. Z.; Chemical Demonstrations, A
Handbook for Teachers of Chemistry, Volume 2, University of Wisconsin
Press,
1985; pp 214 ? 215; (c) Gilbert, G. L., Alyea, H. N., Dutton, D., and
Dreisbach,
D., Tested Demonstrations in Chemistry and Selected Demonstrations from
the Journal of Chemical Education, Volume I; Journal of Chemical
Education
1994, pp I-34 - 35.). In each case, ammonia and air react at the
surface of the metal that has been preheated to redness in a
flame.
The exothermic nature of the reaction sustains the red glow of the
catalyst.
In the reaction described here, the palladium catalyst operating at a
lower
temperature yields nitrogen rather than nitric oxide.
Fill the reagent syringe with 30 mL ammonia (1.2
mmol) and 30 mL oxygen (1.2 mmol.) In this proportion, NH3(g) is
the limiting reagent. Connect the reagent and receiver syringes
to
the catalyst tube as shown in the Figure. For this reaction, do
not
pass any of the gas mixture through the catalyst tube to displace air
from
the tube. Heat the catalyst tube evenly on all sides for a total
of about 30 seconds. Slowly pass about half of the ammonia/oxygen
reagent gas mixture through the catalyst tube over the course of about
30 seconds. A cloud or fog of condensing water vapor should be
noticed
in the receiver syringe. After half of the gas mixture has been
passed
through the catalyst tube, remove the heat. Remove both syringes
and cap them with Latex syringe caps. Label the syringes with a
marker
pen.
The relative amount of ammonia in each
syringe
is determined as follows. Note the volume of gas in each
syringe.
Remove the syringe cap and place each syringe in a 250 mL beaker filled
with water. Draw at least 20 mL water into each syringe; ammonia
will quickly dissolve. After a minute, note the new volume of the
gas in the syringe. The product syringe will contain little or no
ammonia, so the volume of gas will be about the same as its original
value.
The reactant syringe had contained 50% ammonia so that the volume of
gas
remaining should be half of its original amount. One may add some
universal indicator to the discharged water from each syringe in order
to estimate the pH. The unreacted ammonia will increase the pH
substantially,
while the product syringe may remain neutral. If nitric oxide
were
produced as occurs with the reactions described in the literature (see
above), it would immediately react with oxygen present to form red NO2,
an acid anhydride. Neither the red color of NO2,
nor the low pH that a solution of the gas would produce is observed.
F. Methane and Nitrogen Dioxide.
CH4(g) + 2 NO2(g)
N2(g) + CO2(g) + 2 H2O(g)
DH = -869 kJ
Fill the reagent syringe with 30 mL methane (1.2 mmol) and 30 mL nitrogen dioxide (1.2 mmol.) This proportion assures that NO2 is the limiting reagent. The mixture is red-brown due to the nitrogen dioxide. Connect the reagent syringe to the catalyst tube and assemble the apparatus as shown in the Figure. Do not pass any of the gas mixture through the catalyst tube to displace air from the tube. Heat the catalyst tube evenly on all sides for a total of about 30 seconds. Slowly pass all of the CH4/NO2 reagent gas mixture through the catalyst tube over the course of about 30 seconds. The gases collected in the receiver syringe should not be red. Rather, a 'fog' of water vapor should be noted. It is possible that the red color will not completely disappear on the first pass. If that is so, simply reverse directions and pass the gas mixture back through the catalyst in the other direction.
In addition to detecting the
reaction has taken place due to the disappearance of the red color, the
product gases, described in Part Three, can be tested by the
(a) Limewater testThis reaction is highly suited for a lecture demonstration because the red color of the reactants can be seen to disappear while a fog of water forms in the product syringe.
(b) Water test

G. Carbon Monoxide and Nitrogen Dioxide.
4 CO(g) + 2 NO2(g)
N2(g) + 4 CO2(g) DH
= -1198 kJ
Fill the reagent syringe with 40 mL carbon monoxide (1.6 mmol) and 15 mL nitrogen dioxide (0.6 mmol.) This proportion assures that NO2 is the limiting reagent. The mixture is red-brown due to the nitrogen dioxide. Connect the reagent syringe to the catalyst tube and assemble the apparatus as shown in the Figure. Do not purge the catalyst tube with the gas mixture before heating. Heat the catalyst tube evenly on all sides for a total of about 30 seconds. Slowly pass all of the CO/NO2 reagent gas mixture through the catalyst tube over the course of about 30 seconds. The gases collected in the receiver syringe should not be red. Unlike Reaction 6, no 'fog' of water vapor will be noted. It is possible that the red color will not completely disappear on the first pass. If that is so, simply reverse directions and pass the gas mixture back through the catalyst in the other direction.
In addition to detecting the reaction has taken place due to the disappearance of the red color, the product gases can be tested by the Limewater test, described in Part Three.
This reaction will take
place
without the catalyst present if high temperatures are used; this can be
demonstrated by performing the reaction with a control (empty
tube).
The reaction requires a catalyst at lower temperature.
H. Decomposition of Nitrous Oxide
The thermal decomposition of nitrous oxide occurs above 300 oC. The reaction is:
2 N2O(g)
2 N2 (g) + O2 (g) DH
= -164 kJ
Fill the reagent syringe with 60 mL N2O (2.4 mmol N2O). Connect both the reagent and receiver syringes to the catalyst tube and assemble the apparatus as shown in the Figure. Pass about 10 mL of N2O through the catalyst tube to displace the air present. Disconnect the receiver syringe from the catalyst tube, discharge the 10-mL gas from the receiver syringe and reconnect to the catalyst tube. Heat the catalyst tube evenly on all sides for a total of about 45 seconds. Slowly pass about half of the N2O(g) through the catalyst tube over the course of about 30 seconds. The catalyst may turn slightly tan due to oxidation caused by the oxygen produced by this reaction. After half of the gas mixture has been passed through the catalyst tube, remove the heat. Remove both syringes and cap them with Latex syringe caps. Label the syringes 'reactants' and 'products' with a marker pen.
Test the reagent gas
mixture
and product gas mixture by the following tests, described in Part Three:
(a) Glowing Splint test
(b) Gas Chromatography
I.
Nitrous
Oxide and Ammonia
3 N2O(g) + 2 NH3(g)
3 H2O(g) + 4 N2(g) DH
= -880 kJ
Fill the reagent syringe with 15 mL ammonia (0.6 mmol) and 30 mL nitrous oxide (1.2 mmol.) In this proportion, NH3(g) is the limiting reagent. Connect the reagent and receiver syringes to the catalyst tube as shown in the Figure. Do not purge the catalyst tube with the reaction mixture. Heat the catalyst tube evenly on all sides for a total of about 30 seconds. Slowly pass about half of the NH3/N2O reagent gas mixture through the catalyst tube over the course of about 30 seconds. After half of the gas mixture has been passed through the catalyst tube, remove the heat. Remove both syringes and cap them with Latex syringe caps. Label the syringes with a marker pen.
Perform the tests, described
in Part Three, on the on the reagent gas mixture and product gas
mixture:
(a) Acidity testJ. Nitrous Oxide and Carbon Monoxide
(b) Ammonia test
(c) Water test
N2O(g) + CO(g)
CO2(g) + N2(g) DH
= -365 kJ
Fill the reagent syringe with 30 mL carbon monoxide (1.2 mmol) and 30 mL nitrous oxide (1.2 mmol.) Connect the reagent and receiver syringes to the catalyst tube as shown in the Figure. Pass about 10 mL of gas mixture through the catalyst tube to displace air from the tube. Remove the receiver syringe from the catalyst tube, discharge the contents and reconnect as before. Heat the catalyst tube evenly on all sides for a total of about 30 seconds. Slowly pass about half of the CO/N2O reagent gas mixture through the catalyst tube over the course of about 30 seconds. Remove the heat. Remove both syringes and cap them with syringe caps. Label the syringes with a marker pen.
Perform the following tests,
described in Part Three, on the reagent gas mixture and product gas
mixture.
(a) LimewaterDo not perform the Glowing Splint test on unreacted N2O(g)/CO(g) mixture; this mixture of gases reacts explosively.
(b) Flammability
(c) Gas Chromatography
K. Nitrous Oxide and Methane
4 N2O(g) + CH4(g)
CO2(g) + 4 N2(g) + 2 H2O(g)
DH = -1130 kJ
Fill the reagent syringe with 40 mL N2O (1.6 mmol) and 10 mL methane (0.41 mmol.) Cap the syringe and allow the gases to mix for several minutes. Connect the reagent syringe to the catalyst tube and assemble the apparatus as shown in the Figure. Pass about 10 mL of gas mixture through the catalyst tube. (Option: Remove the receiver syringe from the catalyst tube, discharge the 10-mL air from the receiver syringe and reconnect to the catalyst tube.) With a Bunsen burner on low heat (no sharp inner cone), heat the catalyst tube evenly on all sides for a total of about 30 seconds. Remove the heat; it is NOT necessary to continue to heat the catalyst. Slowly pass about half of the CH4/N2O reagent gas mixture through the catalyst tube over the course of about 30 seconds. The catalyst inside the tube may become red hot, in which case slow down the flow of gas. Small droplets of water may form on the glass near the receiver syringe. A cloud of condensing water vapor may also be noted in the receiver syringe. After half of the gas mixture has been passed through the catalyst tube, remove the heat. Remove both syringes and cap them with latex syringe caps. Label the syringes with a marker pen.
One or more of the following
tests, described in Part Three, may be performed on the reagent gas
mixture
and product gas mixture:
(a) Limewater test for CO2
(b) Flammability test:
(c) Gas chromatography.
(d) Water test
L. Trying
Other Catalytic Reactions.
Use caution when
attempting
other reactions with the catalyst tube. Explosive mixtures, even
on the millimole scale are dangerous. When trying reactions for
the
first time, dilute the gas mixture with an inert gas such as argon or
nitrogen.
For example, NO2 and H2
react
explosively unless diluted. The catalyst glows red and then the
explosion
occurs. In our case, the plunger shot out of the syringe, but the
glass catalyst tube could have just as easily exploded. When new
reactions are being explored, they should be done so with considerable
dilution (perhaps 90% argon and 10% reagents) until the nature of the
reaction
has been worked out. Never use pure oxygen as an oxidant unless you
have
determined it is safe to do so. This is done by a series of
experiments
in which the amount of O2 is incrementally
increased.
We used this approach in working with Reactions C and E.
Generally
air can be used as ‘diluted oxygen;’ it is approximately 21% O2
and the rest is inert N2 and Ar.
A. Acidity test.
Prepare a universal
indicator
by dissolving 5 mL universal indicator in 50 mL distilled water.
The concentration must be fairly high so that the colors are readily
seen.
Equip the syringe with a 15 cm length of latex tubing. Bubble 10
- 20 mL of the gas through the indicator solution. Remove the
syringe
and tubing. Notice color changes.
B. Ammmonia test
Ammonia can be detected by odor. Discharge 3-mL of the gas about 1-ft (30 cm) in front of your face. With a cupped hand, waft the gas towards your nose. Ammonia can also be detected by the Cu+2 test. Place 5 mL 0.10 M CuSO4 in a 15 x 180 mm test tube. Equip the syringe with a 15 cm length of latex tubing. Bubble 10 - 20 mL of the gas through the Cu+2 solution. Remove the syringe and tubing. Stopper the solution and shake to mix gaseous layer with Cu+2 solution. A deep blue solution indicates the presence of NH3 as a result of the reaction:
Cu+2(aq) + 4 NH3(g)
[Cu(NH3)4]+2(aq)
C. Bromine-water test.
Place 5 mL dilute bromine water (yellow, not orange) into a 15 x 180 mm test tube. Equip the syringe with a 15 cm length of latex tubing. Bubble 10 - 20 mL of the gas through the bromine water solution. Remove the syringe and tubing. Stopper the solution and shake to mix gaseous layer with bromine water solution. If alkenes are present, such as ethene, the yellow solution will turn colorless. The reaction is:
C2H4(g)
+ Br2(aq)
CH2OHCH2Br(l)
Other gases, including
ethane,
CO2, and H2 do not react
with
bromine water, so the solution will not discolor. (Bromine water
is prepared from chlorine bleach and potassium bromide or sodium
bromide.
For detailed instructions, see our gas chemistry website (Part Four,
below).)
D. Flammability test.
Fill a small weighing
boat with 3% dish soap solution. Equip the gas syringe with the
15-cm
length of latex tubing. Discharge 10-mL gas into the soap
solution
in order to produce a mound of several large bubbles. Try to
ignite
the bubbles with a match. If the bubbles contain hydrocarbons,
they
may burn or pop rather than simply break. (Dish soap solution,
3%,
is prepared by dissolving 3 g dish soap per 100 g water.)
E. Gas chromatography.
We use gas
chromatography
to separate and detect syringe gases. Our choice of column is a
Porapak
N 80/100, 6-ft (180 cm), inside diameter = 0.085 inches (2.2 mm),
available
from Alltech Part Number 2716; telephone: 847-948-8600. We use a
thermoconductivity detector and run the GC at room temperature.
Carrier
gas is helium, 30-mL/minute.
F. Glowing Splint test
A traditional test for
oxygen is the glowing splint test. Only one other common gas, N2O
is capable of re-igniting a glowing splint. Connect the syringe to a
glass
pipet via a short length of latex tubing. Discharge 10 - 15 mL of the
gas
directly from the syringe onto the glowing splint. The discharge
should be quick and as close to the glowing splint as possible.
Pure
O2 and N2O will re-ignite
the
splint into an open flame. Mixtures of these gases with other
gases
may prevent the splint from being re-ignited, however the splint will
glow
brightly while the gas is being discharged. In most cases, the
splint
will re-ignite, however.
G. Limewater test
Place 3 - 4 mL lime water in a 15 x 180 mm test tube. Equip the syringe with a 13 cm length of latex tubing. Discharge 10 - 20 mL of the gas above the surface of the limewater solution. Remove the syringe and tubing. Stopper the solution and shake to mix gaseous layer with limewater solution. A cloudy solution indicates the presence of CO2 as a result of the reaction:
Ca(OH)2(aq) + CO2(g)
CaCO3(s) + H2O(l)
(Limewater is a clear colorless saturated Ca(OH)2(aq)
prepared by mixing 1.5 g Ca(OH)2(s) per liter of water. Stir or
shake
vigorously and allow the solid to settle overnight. When using
limewater,
decant carefully to avoid transferring any solid or suspended Ca(OH)2(s).)
H. Water test
When water is formed,
the product syringe often appears 'cloudy' from the aerosol of
water.
After a few minutes, the aerosol condenses into minuscule drops of
water
lining the inside of the syringe. By pushing the plunger inward
by
5 - 10 mL and then retracting it back outward by the same amount, the
water
droplets are pushed along ahead of the plunger. This greatly
assists
in seeing the droplets. As chemical confirmation, remove the
plunger
just long enough to add a piece of blue-colored Dririte (CoCl2
on an anhydrous CaCl2 granule) to the
syringe.
Return the plunger or stopper the syringe barrel. The presence of
water is confirmed if the blue granule turns pink-purple within a few
minutes.
If the glass housing
should
break, return the ceramic catalyst support (not the glass) to
Educational
Innovations for repair! The ceramic support is fragile and should
be packed in a sealed plastic bag and cushioned accordingly to prevent
breakage during shipping. Include $6.50 per tube and $4.95 for
shipping
and handling (2000 prices). Include your name, shipping address,
e-mail address and telephone number with your repair order.
B. Our Gas Chemistry Website
We have published 16 articles in Chem 13 News (with several more on the way!) describing the microscale preparation and experimentation for a wide variety of gases. All of these articles are available on our gas chemistry website or in our book on microscale gas chemistry experiments which is at:
http://mattson.creighton.edu/Microscale_Gas_Chemistry.html
This work with the catalyst
tube refers to four different chapters in this website or in our book
on
microscale gas chemistry experiments . Interested readers are
encouraged
to learn more about microscale gas chemistry by visiting this
site.
In all, over 140 experiments are described along with many spectacular
photographs of the reactions.
C. Microscale Gas Chemistry Book
Own your own copy of all of
the microscale gas chemistry experiments published in our Chem 13
News
series. The book includes a detailed index, ordering information
and information about each gas. Spiral bound, 270+ pages.
Sold
exclusively by Educational Innovations, Item #BK-590, $29.95.
D. Ordering syringes, parts, etc. from Educational Innovations
• gas reaction catalyst tube only (Item # GAS-120)
• syringes, 60-mL plastic syringe with a LuerLOK fitting (Item # GAS-140)
• syringe cap fittings, latex LuerLOK (Item # GAS-160)
• plastic vial caps (Item # GAS-180)
• latex tubing, 1/8-inch (3.175 mm) ID, 5 ft (1.75 m) lengths (Item # GAS-220)
• metal locking hemostat (Item # GAS-200)

JC standing
by her St Albert's Day poster, Creighton University, November 11, 2002