Carl Schroedl
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THE EFFECT OF VARYING ELECTROLYTIC
CONCENTRATION ON HYDROGEN PRODUCTION
Candidate Name: Carl Schroedl Advisor: Mr. John Pearson
Candidate Number: 000477237 Word Count: 3,997
Category: Chemistry Year: 2008
Center Name: Southwest
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Abstract
Hydrogen has the potential to wean society off of the expensive and
environmentally detrimental hydrocarbons currently used to meet energy demands.
While proton exchange membranes will be applied in many roles such as
transportation, initial production of hydrogen fuel will come from the electrolysis of
water using alkaline electrolytes.
By applying electrochemical theory and extensive dimensional analysis, an
equation was developed that was thought to describe the relationship between the
molarity of the electrolytic solution and the volume of gas produced in a fixed time.
Many homemade electrolyzer designs were experimented with before settling on one
suitable to the experiment. Sodium hydroxide solutions of varying molarities were
allowed to electrolyze under a eudiometer for 10.0 minutes before the volume of
hydrogen and oxygen gas was recorded.
Although the experimental results did not agree in quantity or in trend with the
relation defined in this paper, foundations of an accurate equation may have been laid.
Appendices include graphics, photographs and discussions of electrolyzers, a
Materials Safety Data Sheet, and suggestions for further research into neglected areas
of science that may soon become significant.
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Acknowledgements
The author would like to express gratitude to the following individuals who contributed
significant time, resources, advice, energy or other support to this project:
Sherwood Bergseid: Consultation on ionic mobility
Nathan Ostberg: Preliminary consultation
Kelsey Ostberg: Preliminary consultation, several text books
John Pearson: Laboratory equipment and supervision, text book, consultation,
commenting on successive drafts.
Paul Schroedl: Obtaining stainless steel mesh and other supplies
Tom Zdrazil: Occasional consultation
Access to the 88th
Edition of the CRC Handbook of Chemistry and Physics was provided by
the University of Minnesota’s Walter Library.
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Contents Page #
Introduction 1-2
Theory 3-12
Oxidation, Reduction, Anodes and Cathodes 3-5
Electrolytes 3-13
Dissociation 5-6
Alkali Hydroxide Electrolytes 6
Conductivity 6-9
Molar Conductivity 8-9
Relating Conductivity to Gas Production 9-12
Experiment 12-23
Background 12-14
Variables 14-15
Electrolyzer 15-18
Electrolyzer Supplies 15-16
Electrolyzer Construction Procedure 16-18
General Materials 18-19
Procedure 19-21
Data Collection and Representation 21-22
Numerical Analysis 23
Conceptual Analysis 23-24
Conclusion 24
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Bibliography 25-26
Appendices 26-48
Appendix A: Extractions from Sources 27-28
Appendix B: Photographs of Constructed Electrolyzers 29-33
Appendix C: Electrolyzer Design 34-39
Appendix D: Materials Safety and Data Sheet of Sodium Hydroxide 40-46
Appendix E: Further Research 48
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Introduction
Many consider hydrogen to be the environmentally benign fuel of the future.
In August, 2006, the US National Renewable Energy Laboratory determined that
“48% of the worldwide production of hydrogen is via large-scale steam reforming of
natural gas” (“Power” 48). Steam reformation of hydrocarbons produces a bevy of
greenhouse gasses and relies on a resource that dwindles and increases in price.
Exhaustive studies done by the Intergovernmental Panel on Climate Change have
asserted that “Greenhouse gas forcing is the dominant cause of warming during the
past several decades,” and that “It is extremely unlikely (<5%) that recent global
warming is due to internal variability alone” (Hegerl et al 727).
Jeremy Rifkin, the President of the Foundation on Economic Trends, envisions
a future in which hydrogen is produced through a distributed network of electrolyzers
(Rifkin, 218). The prospect of distributed electrolysis using renewable sources of
energy is currently costly, but it may be the route of least environmental impact.
Before the hydrogen economy can be realized, much advancement and research must
be done.
The most promising advancement in both electrolyzer and fuel cell technology
has been the proton exchange membrane (PEM hereafter), which allows for minimal
distances between electrodes and complete product separation. Although much
research is being done in this region of polymer science (“Sandia”, “A Micro”),
Dupount's expensive Nafion® membrane remains the most prevalent.
It is prudent to assume that it will be expensive to purchase fuel cells or any
vehicles powered by them. There will be less incentive to invest in such vehicles if
their accompanying electrolyzers are PEM-based (and therefore expensive). In the
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introduction of the hydrogen energy epoch, the domestic, distributed production of
hydrogen via electrolysis will be promoted by the PEM's inexpensive alternative:
alkaline electrolytes. Alkali hydroxides receive widespread use as electrolytes
because the compound almost entirely dissociates in water, resulting in an excellent
electrolytic conductor that persists in the solution.
Although most of the alkaline electrolytes used today reside in the alkali
hydroxide category, there is not a consensus on which of these electrolytes is best
suited for the production of hydrogen, nor an equation relating fundamental
electrolyte-specific properties to production. Although potassium hydroxide appears
to be the most frequently employed in large-scale electrolyzers, phrases like, “In the
past, potassium hydroxide was by far the most common electrolyte used,” (Dicks et al,
271) abound throughout sources, providing no further justification. The
concentrations of electrolytic solutions used for water electrolysis were also found to
vary without explanation in sources. This essay utilizes electrochemical theory to
construct an equation relating the volume of gas produced in a fixed amount of time to
the concentration of the sodium hydroxide solution. The equation will be
experimentally verified by constructing an electrolyzer, varying molarity and
observing the volume of gas produced.
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Theory
As the electrolytic processes required for the production of hydrogen are
complex and interdisciplinary in nature, a thorough explanation of the pertinent theory
must be recounted before any attempt to apply it. To paraphrase Abu Bakr,
knowledge without action is useless and action without knowledge is senseless
(“Sayings”).
Oxidation, Reduction, Anodes and Cathodes
The basic redox reaction that occurs when a current is run through
water is:
222 22 OHOH
This equation represents the overall reaction, not the reactions that occur
locally at each electrode. The electrodes are labeled either cathodes or anodes
depending on whether the electrons are entering or leaving the solution through
them. The nomenclature can be confusing, but the situation can be concretely
established by remembering that cations (positively charged) are always
attracted to cathodes (negatively charged) and anions (negatively charged) are
always attracted to anodes (positively charged.) It is also important to account
for the fact that conventional current is of the opposite sign.
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The addition of electrons at the cathode causes a reduction reaction to
take place.
OHHeOH 2222 22
The hydroxide ions, being the very definition of an Arrhenius base, contribute
to significant alkalinity at the cathode. An oxidation reaction ensues at the
anode to complete the set of half-reactions.
eHOOH 442 22
At the cathode the water molecules are reduced, producing both
hydrogen, which is attracted to the cathode, and hydroxide ions, whose
negative charges propel them toward the anode. Meanwhile at the anode, the
Cathode ( - ) Anode ( + )
+
+
+
-
-
-
Cation Anion
+ -
Direction of Electron Travel
Power Supply
Alkaline Region Acidic Region
Electrolysis
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oxidation of water molecules produces oxygen, which is attracted to the anode,
and hydrogen ions, whose positive charges propel them toward the cathode and
the hydroxide ions that it just produced. The cathode’s hydroxides and the
anode’s hydrogen ions react somewhere in between the electrodes, producing
water. For a visual representation of this process, see Appendix B.
Electrolytes
The previous equations neglect the fact that water has preciously few
conductive ions; in pure water at 25° C, hydrgen and hydroxide ions are
present in concentrations of 1×10-7
moles per liter (Pauling, 482). Pure water
has a conductivity of 4.4×10-4
ohm-1
cm-1
at 20° C (Pauling, 517). Water’s
lack of conductivity can be improved through the addition of electrolytes.
Electrolytes increase the quantity of ions available in the solution and hence
decrease the average distance and time for ions produced at the electrodes to
encounter an ion of the opposite charge.
Dissociation
Ionically-bonded compounds dissociate in water. Water has a
dielectric constant of about 80 at room temperature; so two oppositely
charged components of an electrolyte attract each other with 1/80 of the
force that they would in air (Pauling, 434). Additionally, when an
electrolyte is introduced into water, the electrolyte’s cations are
attracted to the slightly negatively-charged (-δ) oxygen atoms of the
water. The electrolyte’s anions are attracted to the water’s slightly
positively-charged (+δ) hydrogen atoms (Dorin et al 548).
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Some electrolytes dissociate more than others. Strong
electrolytes dissociate more than weak ones. The degree to which
electrolytes dissociate is quantitatively defined by dissociation
constants. The experiments that determine the constants must maintain
constant temperature, pressure and molarity throughout. The values are
difficult to obtain and usually in error of ± 5% (“Solving”).
Alkali Hydroxide Electrolytes
In Fuel Cell Systems Explained, the authors state that, “In
practice… the only electrolytes in use are alkaline liquids and solid
proton exchange membranes” (Dicks et al, 271). Alkali hydroxides and
dissociate completely in water, create only small amounts of metal
buildup on the cathode and emit no toxic gasses at the anode. For
example, when using sodium chloride as an electrolyte, the chloride
anions deposit their extra valence electrons on the anode and are then
bond with other chlorine atoms to form diatomic chlorine gas.
Chlorine gas it is of no use electrolytically and biologically detrimental.
As a consequence of the shortage of anions, sodium metal could also
form on the cathode in this reaction.
Conductivity
Reliable methods of accurately calculating the theoretical
conductivity of electrolytic solutions are the topics of many projects.
Theoretically, individual ions conduct electricity most efficiently per
mole in an infinitely dilute solution of electrolyte. Ions under the
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influence of the electrodic electric field are also influenced by the
smaller electric fields of the ions of opposite charge.
As an example, assume that an electric field exists between two
electrodes in an aqueous solution containing only one molecule of
monoprotic electrolyte. By chance the dissociated ions start out next to
the electrode of equal charge (i.e. the cation is adjacent to the anode
and vice versa). As the cation is attracted to the cathode, and vice versa,
the electrodic electric field propels the ions across the electrodic gap
and towards each other.
As the ions pass midway between the electrodes they are
attracted to each other, causing them to slow and deviate from their
course. However, the force of attraction between the ions cannot
overcome their attraction to the electrodes and thus they continue on to
their respective electrodes.
+
- anode +
cathode -
1 anode +
cathode -
2
-
anode +
cathode -
4
+
+
-
anode +
cathode -
3
-
+
Actual Path pathpathtravel
Ideal Path
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The mutual attraction between the ions produced little to no
observable change in the example above, though the reaction would
take place at an exceedingly slow rate; considering that individual ions
in water travel between 10-3
and 10-4
cm s-1
and that they would require
2(6.02×1023
) transversals to produce one mole of hydrogen (“Horiba”).
If the same situation is analyzed using a 1 molar solution of electrolyte,
where every anion is attracted to 6.02×1023
cations and vice versa, the
inter-ionic resistance is much greater. Therefore the most efficient
ionic conduction of electricity per mole occurs when ions are infinitely
dilute.
Molar Conductivity
The variation of the conductivity per mole of electrolyte
with respect to the concentration of the electrolyte was defined
by Kohlrausch to be the following for strong electrolytes:
Where is the molar conductivity at infinite dilution reached
by plotting the molar conductivity at various concentrations
vs. concentration and extrapolating to zero concentration, C is
the concentration of the electrolyte in mol cm-3
and k is the
Kohlrausch coefficient, a constant dependent on the electrolyte
(McCarron). and have units of Ω-1
cm2 mol
-1 and k has
units of cm2L Ω
-1mol
-1.
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In order to calculate the molar conductivity of a
binary electrolyte at infinite dilution using pre-determined
experimental values, the following formula is needed.
Here both λ terms are ionic molar conductivities, and the
subscripts denote whether they pertain to the cation or anion.
Relating Conductivity to Gas Production
It was noted in the course of background research that there was
a surprising lack of equations devoted to the relation of electrolytic
conductivity to the production of hydrogen and oxygen gas. The
McCarron and Grow resources were particularly helpful in providing
the larger equation’s constituents. To determine the duration of time
required to produce a certain volume of hydrogen and oxygen gas when
voltage is known, pressure is standard, and temperature is 298K, a
preliminary equation that draws on the stoichiometric coefficients of
the reaction, the Ideal Gas Law, the Faraday constant and the relation
of electrical quantities must be used. It is less complicated to calculate
the number of moles in 1.00 L of ideal gas at 298K and standard
pressure before considering the main preliminary equation.
RT
PVn
V=Volume, n=number of moles, R=Ideal Gas Constant,
T=Temperature, P=Pressure
Carl Schroedl
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mol
KmolK
atmL
Latmn 041.0
298082058.0
00.100.1
Substituting this crucial volume, it is possible to make a preliminary
equation. Note that gas refers to both hydrogen and oxygen gasses and
that the Faraday constant is the charge on a mole of electrons defined as
follows:
e
CF
1
10602.1
e mol 1
e 106.02
e mol 1
C 96485.34 19
-
-23
-
Preliminary Equation:
sec C
sec
e mol 1
C 96485.34
gas mol 3
e mol 2
gas L 1
gas mol 0.041gas Lin V
-
t
The only number lacking in this preliminary equation is the amperage.
The amount of current flowing is dependent on the conductivity
equations mentioned earlier. Consider the following equations once
more:
Once the molar conductivity of an electrolyte is known, this quantity
can be used to find the conductivity ( ) of the electrolytic solution of a
known concentration C in mol cm-3
.
Cc
When the equation is solved for κ, κ’s remaining units provide a
revealing path to the resistance that the electrolytic solution produces in
an electrolyzer’s circuit.
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3
2
ccm
molin C
Ωmol
cmin Λ
Ωcm
1in κ
The conductivity ( ) is the reciprocal of the solution’s resistivity (ρ).
RA
d
1
The variables d, the gap between electrodes, and A, the electrodic
parallel surface area, relate κ to resistance (R), a volume-dependent
quantity. When R is solved for using dimensional analysis, it can be
shown that the units cancel, and only resistance in ohms remains.
Ωin Rcm
cmΩ
Ω cm
cm d
cmA cmΩin κ
cm dΩin R
1-21-1-
If a known constant voltage is being applied across the electrodes, the
current passing through the solution can be found by substituting R into
the simple equation that relates current, resistance and voltage.
Ohms R
Volts EAmps I
Since the ampere is defined as one Coulomb per second, substituting
the output of the previous equation into the preliminary equation should
provide a method of determining the time required to produce a given
amount of gas as the concentration of the electrolyte varies. The entire
relation of electrolytic concentration ( M in mol L-1
) to the number of
seconds ( t ) required to produce a volume of gas follows. All included
variables were defined above.
Relation of Electrolytic Concentration to Time:
Carl Schroedl
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sec
Cin
1010
sec
e mol 1
C 96485.34
gas mol 3
e mol 2
gas L 1
gas mol 0.041gas Lin V
36
3
336
3
32
22
0
2
-
t
cmd
cm
m
m
L
L
molM
cm
m
m
L
L
molM
mol
Lcmk
mol
cmAcm
voltsVc
It is experimentally easier to verify to volume of gas produced
via electrolysis in a known time than it is to measure how the length of
time required to generate a given volume of gas. By algebraic
manipulation of the preceding equation, the equation is solved for
volume as follows.
Relation of Electrolytic Concentration to Product Volume:
gas Lin Vgas mol 0.041
gas L 1
e mol 2
gas mol 3
34.96485
e mol 1
sec
Cin
1010
sect -
36
3
336
3
32
22
0
2
C
cmd
cm
m
m
L
L
molM
cm
m
m
L
L
molM
mol
Lcmk
mol
cmAcm
voltsVc
Experiment
Background
Using electrochemical knowledge described in the Theory section as
well as constants obtained from Grow and McCarron, this experiment attempts
to verify aforementioned relation of concentration to time by electrolyzing an
electrolytic solution of known concentration and measuring the time required
to produce 50 ml of gas. Several home-made electrolyzers were built and it
was eventually decided that gas separation should be sacrificed for a narrower
electrode gap in order to reduce the time needed to produce measureable
volumes of gas. A summary of electrolyzer design considerations and
alternate designs are included in Appendix C. Sodium hydroxide was chosen
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as the electrolyte because it was the most economically accessible of the alkali
hydroxides, whose benefits were mentioned earlier.
The constants required by the large equation were obtained either by
direct measurement or from credible sources. The area (A) and electrode gap
(d) were measured with a ruler. McCarron provided the values of 0 and
0
at 298 K in12 molm . After converting to Ω
-1 cm
2 mol
-1, the limiting molar
ionic conductivities of the sodium cation and the hydroxide anion are
(respectively): 1210 2.50
molcm 1210 6.197 molcm
Using these two variables, and the equation , Λ0 was calculated.
121121121
0 8.2476.1972.50 molcmmolcmmolcm
It was difficult to find values of the Kohlrausch coefficient ( k ). The
slope of a graph (see Appendix A) of the molar conductivity of NaOH over the
square root of its concentration was used to determine k :
0.5 672
mol
Lcmk
The imprecision of this constant could be the source of some future
discrepancies in experimental results, but no other method was available.
Further research and publication of Kohlrausch coefficients should be
encouraged.
A constant voltage was selected with the interest of both reaction rate
and efficiency in mind. Fuel Cell Systems Explained suggests that the
efficiency ( ) of an electrolyzer should be roughly defined by relating the
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theoretical minimum voltage (1.48 V) required by the reaction to Vc, the
voltage being used in practice (Dicks et al 273).
cV
48.1 V
VVc 96.2
50.0
48.1
A target efficiency of 50%, or rather 2.96 V was judged to produce an
acceptable rate of reaction.
The production of gas over water should consider the partial pressures
of water vapor to see how it affects the volume of the gas. When the
eudiometer is lifted or lowered so that the internal waterline is at the external
waterline, it is ensured that the pressure is equal to that of the atmosphere. The
variation of the pressure inside the eudiometer will be ±5%; the local pressure
may be slightly different than 1.0 atm and the eudiometer cannot be held in a
very precise position. The pressure’s significant figures cause the water
vapor’s addition to the volume collected inside the eudiometer to be negligible.
Variables
The molarity of the solution will be the manipulated variable. The
responding variable will be the volume of gas produced in 600 sec (10 min).
The experiment will take place with a constant pressure of approximately 1.0
atm and a temperature of 298 K. The following constants will be assumed:
0.01 96.2 VVc 0.5 672
mol
Lcmk A = 7.1cm
2±0.1 d = 0.1cm±0.05
The values of constants Vc and k are discussed in previous sections. The value
of A is the parallel surface area of the electrodes (or simply width×length of
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one electrode assuming they are the same size) and d is the gap between the
electrodes.
Hypothesis
Assuming constant pressure, temperature, Kohlrausch coefficient,
parallel electrodic surface area, electrodic gap, and molar conductivity, all of
which have been given values in the Variables section, the volume of gas
produced in 10 minutes via the water electrolysis of an electrolytic solution of
sodium hydroxide will vary with the molarity of the solution according to the
equation:
Lin Vgas mol .041
gas L 1
e mol 2
gas mol 3
34.96485
e mol 1
sec
1.0
1010678.2471.7
96.2
sec 600-
36
3
336
3
32
222
C
Ccm
cm
m
m
L
L
molM
cm
m
m
L
L
molM
mol
Lcm
mol
cmcm
volts
Due to the relatively inexpert construction of the electrolyzer, the results are
not expected to match the values of the equation, but should reflect the general
trend.
Electrolyzer
Electrolyzer Supplies
1 cylindrical plastic container with a capacity of 1 L
25 cm2 of stainless steel mesh with 5.5 wires cm
-1 as measured on
an edge as in diagram
15 cm2 fiberglass mesh with 5.5 wires cm
-1
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Hot glue gun, glue
1 metal rod whose length is twice the container’s height and whose
diameter is between 0.5 and 3 centimeters
Small, angled razor
1 pair of sharp shearers
Electrolyzer Construction Procedure
Measure the inner diameter (ID) of the eudiometer being used.
Cut two strips of metal mesh, each with the dimensions 10cm (ID -
0.1 cm) so that the electrodes slide in and out of the eudiometer. It may
help to straighten the wire mesh before continuing. Bend 2 cm on the
end of the mesh strip so that it is perpendicular to the main length of
electrode. Cut out one strip of fiberglass mesh with the same
dimensions as the stainless steel mesh. Sandwich the fiberglass
between the two electrodes, arranging the electrodes as in the assembly
diagram below. Most hot glue guns should be plugged in now. Ensure
that the electrodes make no direct contact. A multimeter with a circuit
continuity tester can ensure this when a probe is placed on either
electrode. Holding this assembly together, insert it into the eudiometer
that will be used. If it will not fit, trim as needed.
Add hot glue to the tip of the electrodes and at the T-shaped
juncture as depicted in diagram. While the glue cools, cut a small
rectangular slit into the center of the bottom of the container. The slit
should be just wide enough for the electrodes to pass through. Once
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the glue on the electrodes cools, insert the electrodes through the slit
and turn the container’s bottom upwards.
Hot glue the area where the container meets the electrodes,
ensuring that the electrodes will be perpendicular to the bottom of the
container. After the glue cools, trim any excess fiberglass mesh
hanging from the bottom. Flip the container. Apply hot glue to the tip
of the long rod. Quickly use the rod’s hot glue to seal the area where
the electrodes meet the container. The glue will cool quickly. Remove
the glue and apply fresh hot glue as needed. Let cool. Test to see if the
seal is complete by filling the container with water and resting it on a
cup and waiting one hour. If an appreciable volume of water has
accumulated in the cup after an hour, additional coatings of glue should
be applied as defined above.
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General Materials
Electrolyzer (see above)
130 g NaOH
8 L deionized water
Electronic balance
1 Weight boat
1 Graduated eudiometer with capacity of 100 ml
1 Stopper for mentioned eudiometer
1 Pair of thick rubber gloves
4 Large rubber stoppers
1 Multimeter accurate to the mV
Stainless steel mesh
Fiberglass mesh
Hot glue
Assembly Diagram
Container
Solution
Waterproof Seal
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1 10-Ampere power supply with variable potential (2.96 V D.C. desired).
2 Scoopulas for handling NaOH
1 Test tube brush with handle longer than eudiometer’s length
8 Beakers, each with a capacity of 1 L (less beakers is permissible, but will
require more rinsing)
Stopwatch
Access to tap water
Medium gauge copper wire
1 water container at least as tall as the eudiometer and wide enough for a
clenched fist to pass through.
Procedure
Warning: Sodium hydroxide is caustic and dangerous if handled improperly.
Consult the Materials Safety Data Sheet in Appendix D before continuing.
Wear gloves, apron and goggles to prevent injury. Hydrogen and Oxygen
form an explosive mixture. Do not experiment near open flame.
The barometric pressure and temperature should be tested at the
location before starting experiment. If any values differ by more than 5%,
consider another day, or readjust equation constants. Use the electronic
balance, the scoopulas, large beakers, deionized water and sodium hydroxide
to produce two 1 liter solutions for each of the following concentrations (mol
L-1
): 0.01 M, 0.1 M, 0.5 M, and 1.0 M. Cover each filled beaker to maintain
purity. Fill the tall, narrow container with tap water. Fasten or solder wire to
the extensions of the electrodes underneath the container. Prevent a short
Carl Schroedl
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circuit by using the four large stoppers to support the container throughout the
trials. Connect the loose ends of the wires to the power supply. Set the power
supply’s potential to 2.96 V. Turn off the power supply. Repeat the following
numbered steps, varying the molarity in the following order: 0.01 M, 0.1 M,
0.5 M, 1.0 M, 0.01 M, 0.1 M, 0.5 M, and 1.0 M
1. Pour the solution of selected concentration into the electrolyzer until
the water level is at least 1 cm above the top of the electrodes. Overfill
the eudiometer with the remainder of the solution.
2. Seal the end of the eudiometer using a thumb or a stopper.
3. Invert the eudiometer and ensure that no bubbles rise to the top. If they
do, return the eudiometer to its former orientation, add more solution,
close the end and repeat this step until no bubbles rise.
4. Place the mouth of the eudiometer underneath the fluid level of the
electrolyzer and release the stopper or thumb. Raise the mouth above
the electrode height, but below the fluid level. Lower the eudiometer
until it rests on the electrodes’ base.
5. Turn on the power supply and start the stopwatch simultaneously. Wait
10 minutes.
6. After 10 minutes, turn off power supply. Allow 2 minutes for the gas
bubbles to collect in the top of the eudiometer. Tap and/or jostle the
eudiometer to dislodge the bubbles.
7. Repeat step 2.
Carl Schroedl
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8. Transfer to tall, narrow container. Release the stopper underwater.
Raise or lower the eudiometer until the level of the solution within
equals the outer water level.
9. Record the volume on a table next to the molarity of solution used.
10. It is safe in most localities to dump the range of concentrations used in
this investigation into the sanitary sewer. Check your local guidelines
and then dump out the solution from the electrodes’ container and
eudiometer. Rinse the electrodes and the involved containers
thoroughly, preferably with pressurized water.
Data Collection and Representation
Trial Molarity (mol/L)
Error (+/-
mol/L)
Volume of Gas (L)
Error (+/- L)
Comments Average
Volume (L) Error of Average Volume (+/-L)
1 0.01 0.002 0.0052 0.0004 unable to equalize
inner and outer fluid levels
0.0062 0.0004 2 0.01 0.002 0.0072
1 0.10 0.002 0.0432 0.0001
0.0447 0.0001
2 0.10 0.002 0.0461
1 0.50 0.002 0.0846 0.0001
0.0815 0.0001
2 0.50 0.002 0.0784
1 1.00 0.002 0.0954 0.0001
0.0940 0.0001
2 1.00 0.002 0.0926
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Volume of Gas vs. Molarity
0.01 ± 0.002, 0.0062 ±
0.0004
0.10 ± 0.002, 0.0447± 0.0001
0.50 ± 0.002, 0.0815 ±
0.0001
1.00 ±0.002, 0.0940 ± 0.0001
y = 0.0193Ln(x) + 0.0933
R2 = 0.9949
0.0000
0.0100
0.0200
0.0300
0.0400
0.0500
0.0600
0.0700
0.0800
0.0900
0.1000
0.00 0.20 0.40 0.60 0.80 1.00
Molarity (mol/L)
Vo
lum
e (
L)
Average Volume of Gas (L) Logarithmic Regression
Error bars were added to each point, but their presence is difficult to discern.
Theoretical and Experimental Comparison
y = 0.0193Ln(x) + 0.0933
R2 = 0.9949
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
0 0.2 0.4 0.6 0.8 1
Concentration (mol/L)
Vo
lum
e (
L)
f(x)=600*(2.96*((7.1*(247.8-67*SQRT(x/1000000))*(x/1000000))/0.1))*(1/96485.34)*(3/2)*(1/0.041) in L
Experimental Volume (L)
Logarithmic Regression
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Numerical Analysis
The experimental data is linearly approximated on the interval of .01 M
- 1.0 M by the equation y = 0.0787x + 0.0249 where R2 = 0.8063. For the
concentrations dealt with in this experiment, the pictured logarithmic
approximation (y = 0.0193Ln(x) + 0.0933) is much more accurate (R2 =
0.9949). The linear equivalent (R2=1) of the proposed equation was found to
be y = 2E-05x + 6E-10 on the same interval, while an accurate logarithmic
approximation could not be found.
Conceptual Analysis
The gradual buildup of sodium on the cathode could have influenced
results, but observations and precautions taken in the experiment should have
minimized this impact. A visual inspection of the electrodes before each trial
did not discover any difference in between trials. Additionally, the electrodes
were rinsed with a high-pressure jet of water after every trial. The results of
the second trials were not consistently greater or smaller than the first trials.
The experimental results seem more conceptually valid than the results
predicted by the equation. If the proposed equation were correct, it still
wouldn’t account for electrolyzer inefficiencies. Therefore, the volume
produced would always be less than the expected. As the results produce more
than theoretically possible, the equation’s accuracy is doubtful. The equation
should be a logarithmic or root function; every instance molarity is increased,
the molar conductivity decreases. The volume should also decrease as the
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molarity of the solution approaches the solubility of the electrolyte in water
because undissociated electrolytes would likely have a high dielectric constant.
Conclusion
Presently the experimental data does not match the proposed relation of gas
volume to concentration in value or in shape in the interval of 0.01 M - 1.0 M. The
hypothesis must be rejected because the volumes produced do not closely match the
shape of the proposed equation. The error in the equation doubtlessly lies in the
complicated numerator. Some error may have occurred in the conversion to electrical
impedance. Although the suggested model is inaccurate, it may prove to be a useful
base for further research (See Appendix E) into this worthy area of electrochemistry.
Carl Schroedl
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Bibliography
Brown, Theodore; Bursten, Bruce; LeMay, H.; Murphy, Catherine. Chemistry: The Central
Science. Pearson Education Inc. Upper Saddle River, New Jersey. 2006.
CRC. The Handbook of Chemistry and Physics. CRC Press. Cleveland, OH. 2007.
Dicks, Andrew; Larminie, James Fuel Cell Systems Explained. John Wiley & Sons Ltd.
West Sussex, England. 2003.
Dorin, Henry; Demmin, Peter; Gabel, Dorothy. Chemistry: The Study of Matter. Prentice-
Hall, Incorporated. Needham, Massachusetts. 1989
Egel, Geoff “IceStuff.com: Build your own own …”
http://www.icestuff.com/~energy21/electrolysis.htm 8/15/07
Faraday, Hittorf, Kohlrausch “The fundamental laws of electrolytic conduction…”
http://www.openlibrary.org/details/fundamentallawso00goodrich 12/20/07
Grow, James M. “Conductivity of Electrolytic Solutions” http://www-
ec.njit.edu/Electrochemistry 8/22/07
“The Hartee-Fock Method” http://www.chm.bris.ac.uk/pt/harvey/elstruct/hf_method.html
8/19/07
“Horiba: The Story of Conductivity”
http://www.jp.horiba.com/story_e/conductivity/conductivity_03.htm 8/21/07
Hamereli, Gabriele; Zwiers, Francis et al “Understanding and Attributing Climate Change”
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch09.pdf 11/29/07
“Ionization Energy” http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/ionize.html#c1
8/19/07
McCarron, Tanner. “Tanner’s General Chemistry.” http://www.tannerm.com/ 24/11/2007
“A Micro Hydrogen Air Fuel Cell” http://stinet.dtic.mil/cgi-
bin/GetTRDoc?AD=ADA440192&Location=U2&doc=GetTRDoc.pdf 08/23/07
“MSDS Search” http://www.mallbaker.com/Americas/catalog/default.asp?searchfor=msds
12/22/07
“Nafion Acidity” http://www.permapure.com/TechNotes/Nafionacidity.htm 8/22/07
Pauling, Linus. General Chemistry. Dover Publications. Mineola, New York. 1988
Carl Schroedl
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“Over Unity Power” http://www.oupower.com 8/20/07
“Power Technologies Energy Data Book”
http://www.nrel.gov/analysis/power_databook/docs/pdf/39728_complete.pdf 8/22/07
Rifkin, Jeremy. The Hydrogen Economy. Jeremy P. Tarcher/Penguin. New York. 2003.
“Sandia polymer electrolyte membrane …” http://www.sandia.gov/news-center/news-
releases/2004/renew-energy-batt/microfuel.html 8/22/07
“Sayings of Abu Bakr” http://muslim-canada.org/sayingsabubakr.html#knowledge 8/19/07
Shermer, Michael. Why People Believe Weird Things. Henry Holt and Company. New York.
2002.
“Sodium: History” http://nautilus.fis.uc.pt/st2.5/scenes-e/elem/e01110.html 1/03/08
“Solving Weak Base Problems” http://www.dbhs.wvusd.k12.ca.us/webdocs/AcidBase/Kb-
Solving1.html 8/23/07
Carl Schroedl
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Appendix A: Extractions from Sources
Extraction from Linus Pauling’s General Chemistry
pg. 518
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Extraction from Grow’s Webpage
Use Kohlrausch’s equation:
The molar conductivity at infinite dilution is known to be 247.8. The concentration and molar
conductivity of the rightmost point on the line above can be estimated. The equation can be
solved for the variable k. 24.18.247150 k
k=67
~250
~150
~1.40
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ABS pipe caps added to weigh down bottles and prevent them from shifting away from
parallel.
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Flex Model
Flex and Two-Bottle Models.
Mesh was wrapped around tubing to maintain shape.
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Appendix C: Electrolyzer Design
Electrolyzer Design
The main considerations in electrolyzer design are gas separation, parallel electrode
surface area, electrode distance and current density. Separation of the product gasses is
crucial because if cross-contamination occurs, a very explosive mixture results. This mixture
is not useful when used in fuel cells. In electrolyzers, and in general, electricity takes the path
of least resistance, which, barring some form of insulation, is the shortest path available.
Decreasing the distance between the electrodes decreases resistance. Increasing the surface
area of both electrodes allows increased amperage. Voltage supplied to the electrolytic
solution need only be in the range of 1.48 to 2.0 volts according to the standard reduction
potential of water (Pauling 529, Dicks et al 273).
Many different electrolyzer designs exist. A very common demonstration model is
known as the Hoffman apparatus. The device is constructed of three thin glass tubes, two
electrodes, two stopcocks, and a bulbous electrolyte addition area. These models are
expensive, and not very efficient, but their transparency allows students to view the reaction
take place. The main cost associated with this design, indeed with many designs, is the
platinum electrodes. Platinum is ranks high in terms of nobility and thus is less likely to
degrade during the reaction. Platinum is also a good conductor. The delicate glassware
associated with Hoffman apparatuses is costly as well.
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Although porous platinum electrodes improve the efficiency of the process, the long,
non-linear path that the electricity must travel provides extensive resistance. One advantage
of the design is that the gasses are fully separated. Another advantage that the Hoffman
electrolyzer has is the fact that, because water is virtually incompressible, the gas is
compressed and can be released directly into a high-pressure storage tank. Of course, if the
gas pressure was allowed to build up too high, the glass shards of the resulting explosion
would be a hazard to anything nearby.
To promote distributed generation, electrolyzers should be neither dangerous
nor expensive. In fact, medium-scale electrolyzers are not difficult to construct. In
homemade devices, electrical energy could be supplied to electrolyzers via a standard ATX
computer power supply if the sense wire (pin 14 on MOLEX connector) were shorted to
Carl Schroedl
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ground and a small load were attached. The load could take the form of a large resistor or
spare computer device, such as an optical or hard drive. Newer power supplies have multiple
+3.3 volt, high amperage wires that could be attached to the electrodes in parallel for
electrolysis.
Several homemade designs have surfaced on the internet that favor a devices whose
appearances are akin to the letters “E” and “U” (Egel, “Over”). Devices favor
polyvinylchloride (PVC) pipes or tubing because of the ubiquity, inexpensiveness and non-
interfering nature of the material. The E-shaped devices are similar to the Hoffman
electrolyzer, and consequently suffer from the same inefficiencies of imprudent electrode
placement; the closer the electrodes are placed, the more likely that products will mix and
escape through the central column. The U-shaped electrolyzers allow for narrower electrode
gaps, but makes gas separation more difficult. Both designs are able to pressurize the reaction
products. Neither design maintains the transparency of the Hoffman electrolyzer, unless clear
PVC pipe is used. At the time of writing, clear PVC pipe was expensive at local and online
retailers. Homemade electrodes are made of relatively inexpensive stainless steel mesh.
Mesh has a high surface area to volume ratio and is usually hand-malleable so that those
without machining experience or equipment can construct the devices as well. The “U”
model was the first constructed in this investigation.
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Another homemade design conceived and constructed in this study takes advantage of
even more widely-available materials. Two modified plastic soft drink containers can be used
as the outer walls of the device. Barbed hose connectors are secured to each bottle cap via
washer and nut. Approximately 90° of each bottle’s circumference is removed along its flat
vertical length (see diagram). The stainless steel mesh electrodes are fixed inside each bottle
with a stainless steel screw. Copper leads to the power supply are wrapped around the screws
and waterproofed with hot glue to prevent oxidation. The bottles are placed inside of a
slightly larger container. Once the electrolytic solution has been added to the larger container,
the bottles are inserted and allowed to fill. Afterwards, the bottles are oriented towards each
other to maximize the amount of parallel electrode surface area.
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The Two-Bottle Model was effective, but suffered from a few defects. The large
parallel surface area of the electrodes was partially negated by the electrode gap. The gap,
however, was actually too narrow, because it was observed that a slight cross-contamination
of the gasses took place. The gas can be pressurized by this electrolyzer, as long as the level
of gas remains above the electrodes and the cut-out portion of the wall. Provided that labels
are removed form the bottles and that the larger container is transparent, the process is clearly
visible. If the junction between screw and copper wire is not shielded from the electrolytic
solution, the metals begin to oxidize and slowly lose conductivity until the reaction comes to a
Carl Schroedl
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standstill. As the volume of water is comparatively enormous, the waterline is not visibly
reduced, even after 12 hours of continuous electrolysis at high amperage.
In order to decrease the total volume of water needed and separate the gasses more
effectively, a third design was created. The container for the electrolytic solution was arrow,
flexible, transparent PVC tubing. The tubing was inexpensive when purchased from a local
hardware retailer. The tubing was bent into a “U” shape and held in place by tying sections of
it to a regularly-punctured display board. The electrodes consisted of rolled stainless steel
mesh. It would be difficult to seal any direct copper connection to the mesh, so a short
segment of single-strand stainless steel wire was used as an intermediary. The intermediary
may not have been sufficiently wide or conductive and consequently may have acted as a
resistor to the large current flow. Unfortunately, the small diameter of the tube requires
considerably reduced parallel electrode surface area. The gas separation was the most
complete out of all the constructed devices, because the distance between the electrodes could
be easily adjusted. It can be reasonably assumed that in both the Flex and “U” Models the
electrode gap could be decreased if a membrane were placed in between them. In lieu of a
more advanced membrane, a common sponge could be used in future trials where large gas
output and product separation is desired.
Gas separation was deemed unnecessary for the purposes of the main experiment
given the inconvenience of slow reaction rate. The sandwich model was created. It is
detailed in the Electrolyzer Section of the main paper.
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Appendix D: Materials Safety and Data Sheet of Sodium Hydroxide
Obtained via http://www.mallbaker.com/Americas/catalog/default.asp?searchfor=msds
SODIUM HYDROXIDE
1. Product Identification
Synonyms: Caustic soda; lye; sodium hydroxide solid; sodium hydrate
CAS No.: 1310-73-2
Molecular Weight: 40.00
Chemical Formula: NaOH
Product Codes: J.T. Baker: 1508, 3717, 3718, 3721, 3722, 3723, 3728, 3734, 3736, 5045, 5565
Mallinckrodt: 7001, 7680, 7708, 7712, 7772, 7798
2. Composition/Information on Ingredients
Ingredient CAS No Percent
Hazardous
--------------------------------------- ------------ ------------ -
--------
Sodium Hydroxide 1310-73-2 99 - 100%
Yes
3. Hazards Identification
Emergency Overview --------------------------
POISON! DANGER! CORROSIVE. MAY BE FATAL IF SWALLOWED. HARMFUL
IF INHALED. CAUSES BURNS TO ANY AREA OF CONTACT. REACTS WITH
WATER, ACIDS AND OTHER MATERIALS.
SAF-T-DATA(tm)
Ratings (Provided here for your convenience)
-----------------------------------------------------------------------------------------------------------
Health Rating: 4 - Extreme (Poison)
Flammability Rating: 0 - None
Carl Schroedl
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Reactivity Rating: 2 - Moderate
Contact Rating: 4 - Extreme (Corrosive)
Lab Protective Equip: GOGGLES & SHIELD; LAB COAT & APRON; VENT HOOD;
PROPER GLOVES
Storage Color Code: White Stripe (Store Separately)
-----------------------------------------------------------------------------------------------------------
Potential Health Effects ----------------------------------
Inhalation: Severe irritant. Effects from inhalation of dust or mist vary from mild irritation to serious
damage of the upper respiratory tract, depending on severity of exposure. Symptoms may
include sneezing, sore throat or runny nose. Severe pneumonitis may occur.
Ingestion: Corrosive! Swallowing may cause severe burns of mouth, throat, and stomach. Severe
scarring of tissue and death may result. Symptoms may include bleeding, vomiting, diarrhea,
fall in blood pressure. Damage may appear days after exposure.
Skin Contact: Corrosive! Contact with skin can cause irritation or severe burns and scarring with greater
exposures.
Eye Contact: Corrosive! Causes irritation of eyes, and with greater exposures it can cause burns that may
result in permanent impairment of vision, even blindness.
Chronic Exposure: Prolonged contact with dilute solutions or dust has a destructive effect upon tissue.
Aggravation of Pre-existing Conditions: Persons with pre-existing skin disorders or eye problems or impaired respiratory function may
be more susceptible to the effects of the substance.
4. First Aid Measures
Inhalation: Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give
oxygen. Call a physician.
Ingestion: DO NOT INDUCE VOMITING! Give large quantities of water or milk if available. Never
give anything by mouth to an unconscious person. Get medical attention immediately.
Skin Contact: Immediately flush skin with plenty of water for at least 15 minutes while removing
contaminated clothing and shoes. Call a physician, immediately. Wash clothing before reuse.
Eye Contact: Immediately flush eyes with plenty of water for at least 15 minutes, lifting lower and upper
eyelids occasionally. Get medical attention immediately.
Carl Schroedl
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Note to Physician: Perform endoscopy in all cases of suspected sodium hydroxide ingestion. In cases of severe
esophageal corrosion, the use of therapeutic doses of steroids should be considered. General
supportive measures with continual monitoring of gas exchange, acid-base balance,
electrolytes, and fluid intake are also required.
5. Fire Fighting Measures
Fire: Not considered to be a fire hazard. Hot or molten material can react violently with water.
Can react with certain metals, such as aluminum, to generate flammable hydrogen gas.
Explosion: Not considered to be an explosion hazard.
Fire Extinguishing Media: Use any means suitable for extinguishing surrounding fire. Adding water to caustic solution
generates large amounts of heat.
Special Information: In the event of a fire, wear full protective clothing and NIOSH-approved self-contained
breathing apparatus with full facepiece operated in the pressure demand or other positive
pressure mode.
6. Accidental Release Measures
Ventilate area of leak or spill. Keep unnecessary and unprotected people away from area of
spill. Wear appropriate personal protective equipment as specified in Section 8. Spills: Pick
up and place in a suitable container for reclamation or disposal, using a method that does not
generate dust. Do not flush caustic residues to the sewer. Residues from spills can be diluted
with water, neutralized with dilute acid such as acetic, hydrochloric or sulfuric. Absorb
neutralized caustic residue on clay, vermiculite or other inert substance and package in a
suitable container for disposal.
US Regulations (CERCLA) require reporting spills and releases to soil, water and air in
excess of reportable quantities. The toll free number for the US Coast Guard National
Response Center is (800) 424-8802.
7. Handling and Storage
Keep in a tightly closed container. Protect from physical damage. Store in a cool, dry,
ventilated area away from sources of heat, moisture and incompatibilities. Always add the
caustic to water while stirring; never the reverse. Containers of this material may be
hazardous when empty since they retain product residues (dust, solids); observe all warnings
Carl Schroedl
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and precautions listed for the product. Do not store with aluminum or magnesium. Do not mix
with acids or organic materials.
8. Exposure Controls/Personal Protection
Airborne Exposure Limits: - OSHA Permissible Exposure Limit (PEL):
2 mg/m3 Ceiling
- ACGIH Threshold Limit Value (TLV):
2 mg/m3 Ceiling
Ventilation System: A system of local and/or general exhaust is recommended to keep employee exposures below
the Airborne Exposure Limits. Local exhaust ventilation is generally preferred because it can
control the emissions of the contaminant at its source, preventing dispersion of it into the
general work area. Please refer to the ACGIH document, Industrial Ventilation, A Manual of
Recommended Practices, most recent edition, for details.
Personal Respirators (NIOSH Approved): If the exposure limit is exceeded and engineering controls are not feasible, a half facepiece
particulate respirator (NIOSH type N95 or better filters) may be worn for up to ten times the
exposure limit or the maximum use concentration specified by the appropriate regulatory
agency or respirator supplier, whichever is lowest.. A full-face piece particulate respirator
(NIOSH type N100 filters) may be worn up to 50 times the exposure limit, or the maximum
use concentration specified by the appropriate regulatory agency, or respirator supplier,
whichever is lowest. If oil particles (e.g. lubricants, cutting fluids, glycerine, etc.) are present,
use a NIOSH type R or P filter. For emergencies or instances where the exposure levels are
not known, use a full-facepiece positive-pressure, air-supplied respirator. WARNING: Air-
purifying respirators do not protect workers in oxygen-deficient atmospheres.
Skin Protection: Wear impervious protective clothing, including boots, gloves, lab coat, apron or coveralls, as
appropriate, to prevent skin contact.
Eye Protection: Use chemical safety goggles and/or a full face shield where splashing is possible. Maintain
eye wash fountain and quick-drench facilities in work area.
9. Physical and Chemical Properties
Appearance: White, deliquescent pellets or flakes.
Odor: Odorless.
Solubility: 111 g/100 g of water.
Specific Gravity:
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2.13
pH: 13 - 14 (0.5% soln.)
% Volatiles by volume @ 21C (70F): 0
Boiling Point: 1390C (2534F)
Melting Point: 318C (604F)
Vapor Density (Air=1): > 1.0
Vapor Pressure (mm Hg): Negligible.
Evaporation Rate (BuAc=1): No information found.
10. Stability and Reactivity
Stability: Stable under ordinary conditions of use and storage. Very hygroscopic. Can slowly pick up
moisture from air and react with carbon dioxide from air to form sodium carbonate.
Hazardous Decomposition Products: Sodium oxide. Decomposition by reaction with certain metals releases flammable and
explosive hydrogen gas.
Hazardous Polymerization: Will not occur.
Incompatibilities: Sodium hydroxide in contact with acids and organic halogen compounds, especially
trichloroethylene, may causes violent reactions. Contact with nitromethane and other similar
nitro compounds causes formation of shock-sensitive salts. Contact with metals such as
aluminum, magnesium, tin, and zinc cause formation of flammable hydrogen gas. Sodium
hydroxide, even in fairly dilute solution, reacts readily with various sugars to produce carbon
monoxide. Precautions should be taken including monitoring the tank atmosphere for carbon
monoxide to ensure safety of personnel before vessel entry.
Conditions to Avoid: Moisture, dusting and incompatibles.
11. Toxicological Information
Irritation data: skin, rabbit: 500 mg/24H severe; eye rabbit: 50 ug/24H severe; investigated as
a mutagen. --------\Cancer Lists\---------------------------------------------------
---
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---NTP Carcinogen---
Ingredient Known Anticipated IARC
Category
------------------------------------ ----- ----------- ----------
---
Sodium Hydroxide (1310-73-2) No No None
12. Ecological Information
Environmental Fate: No information found.
Environmental Toxicity: No information found.
13. Disposal Considerations
Whatever cannot be saved for recovery or recycling should be handled as hazardous waste
and sent to a RCRA approved waste facility. Processing, use or contamination of this product
may change the waste management options. State and local disposal regulations may differ
from federal disposal regulations. Dispose of container and unused contents in accordance
with federal, state and local requirements.
14. Transport Information
Domestic (Land, D.O.T.) -----------------------
Proper Shipping Name: SODIUM HYDROXIDE, SOLID
Hazard Class: 8
UN/NA: UN1823
Packing Group: II
Information reported for product/size: 300LB
International (Water, I.M.O.) -----------------------------
Proper Shipping Name: SODIUM HYDROXIDE, SOLID
Hazard Class: 8
UN/NA: UN1823
Packing Group: II
Information reported for product/size: 300LB
15. Regulatory Information
Carl Schroedl
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--------\Chemical Inventory Status - Part 1\-----------------------------
----
Ingredient TSCA EC Japan
Australia
----------------------------------------------- ---- --- ----- ------
---
Sodium Hydroxide (1310-73-2) Yes Yes Yes Yes
--------\Chemical Inventory Status - Part 2\-----------------------------
----
--Canada--
Ingredient Korea DSL NDSL Phil.
----------------------------------------------- ----- --- ---- -----
Sodium Hydroxide (1310-73-2) Yes Yes No Yes
--------\Federal, State & International Regulations - Part 1\------------
----
-SARA 302- ------SARA 313--
----
Ingredient RQ TPQ List Chemical
Catg.
----------------------------------------- --- ----- ---- ----------
----
Sodium Hydroxide (1310-73-2) No No No No
--------\Federal, State & International Regulations - Part 2\------------
----
-RCRA- -TSCA-
Ingredient CERCLA 261.33 8(d)
----------------------------------------- ------ ------ ------
Sodium Hydroxide (1310-73-2) 1000 No No
Chemical Weapons Convention: No TSCA 12(b): No CDTA: No
SARA 311/312: Acute: Yes Chronic: No Fire: No Pressure: No
Reactivity: Yes (Pure / Solid)
Australian Hazchem Code: 2R
Poison Schedule: S6
WHMIS: This MSDS has been prepared according to the hazard criteria of the Controlled Products
Regulations (CPR) and the MSDS contains all of the information required by the CPR.
16. Other Information
NFPA Ratings: Health: 3 Flammability: 0 Reactivity: 1
Label Hazard Warning: POISON! DANGER! CORROSIVE. MAY BE FATAL IF SWALLOWED. HARMFUL IF
INHALED. CAUSES BURNS TO ANY AREA OF CONTACT. REACTS WITH WATER,
ACIDS AND OTHER MATERIALS.
Carl Schroedl
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Label Precautions: Do not get in eyes, on skin, or on clothing.
Do not breathe dust.
Keep container closed.
Use only with adequate ventilation.
Wash thoroughly after handling.
Label First Aid: If swallowed, DO NOT INDUCE VOMITING. Give large quantities of water. Never give
anything by mouth to an unconscious person. In case of contact, immediately flush eyes or
skin with plenty of water for at least 15 minutes while removing contaminated clothing and
shoes. Wash clothing before reuse. If inhaled, remove to fresh air. If not breathing give
artificial respiration. If breathing is difficult, give oxygen. In all cases get medical attention
immediately.
Product Use: Laboratory Reagent.
Revision Information: No Changes.
Disclaimer: ***************************************************************************
*********************
Mallinckrodt Baker, Inc. provides the information contained herein in good faith but
makes no representation as to its comprehensiveness or accuracy. This document is
intended only as a guide to the appropriate precautionary handling of the material by a
properly trained person using this product. Individuals receiving the information must
exercise their independent judgment in determining its appropriateness for a particular
purpose. MALLINCKRODT BAKER, INC. MAKES NO REPRESENTATIONS OR
WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT
LIMITATION ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE WITH RESPECT TO THE INFORMATION SET FORTH
HEREIN OR THE PRODUCT TO WHICH THE INFORMATION REFERS.
ACCORDINGLY, MALLINCKRODT BAKER, INC. WILL NOT BE RESPONSIBLE
FOR DAMAGES RESULTING FROM USE OF OR RELIANCE UPON THIS
INFORMATION. ***************************************************************************
*********************
Prepared by: Environmental Health & Safety
Phone Number: (314) 654-1600 (U.S.A.)
Carl Schroedl
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Appendix E: Further Research
The relation of gas product to concentration may take on the form of a logarithm of
the concentration minus an asymptotic (1 / (constant-concentration)) component. More
advanced mathematicians should try to describe the shape of this function, including the area
where conductivity approaches a small value related to the conductivity of solid sodium
hydroxide after the molarity of the solution becomes greater than sodium hydroxide’s
solubility. This region of the graph may be useful because electrolysis of sodium hydroxide
itself does produce hydrogen and oxygen gas as was discovered by Humphrey Davy in
1807(“Sodium: History”).
The scarcity of Kohlrausch coefficients nearly put an end to this experiment. Any
effort to find or publish Kohlrausch coefficients is encouraged. Numerous Kohlrausch
constants could also predict the results of a comparison of two electrolytes. These
coefficients could have determined whether it results could be attained for the original focus
of this experiment.
The original focus of this experiment was to determine which alkali hydroxide
electrolyte was more conductive at a variety of molarities. After extensive searching, no
dissociation constants for the alkali hydroxides could be found. The sources consulted
indicated that dissociation constants of alkali hydroxides would be similar and very large.
The virtually complete dissociation of these electrolytes would not have produced results
measurable with the instruments available. Those with more precise instruments could
potentially determine the constants.