IEC 61189-5-2:2015

IEC 61189-5-2 ®
Edition 1.0 2015-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Test methods for electrical materials, printed boards and other interconnection
structures and assemblies –
Part 5-2: General test methods for materials and assemblies – Soldering flux for
printed board assemblies
Méthodes d'essai pour les matériaux électriques, les cartes imprimées et autres
structures d'interconnexion et ensembles –
Partie 5-2: Méthodes d'essai générales pour les matériaux et les assemblages –
Flux de brasage pour les assemblages de cartes imprimées

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IEC 61189-5-2 ®
Edition 1.0 2015-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Test methods for electrical materials, printed boards and other interconnection

structures and assemblies –
Part 5-2: General test methods for materials and assemblies – Soldering flux for

printed board assemblies
Méthodes d'essai pour les matériaux électriques, les cartes imprimées et autres

structures d'interconnexion et ensembles –

Partie 5-2: Méthodes d'essai générales pour les matériaux et les assemblages –

Flux de brasage pour les assemblages de cartes imprimées

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.180 ISBN 978-2-8322-1997-3

– 2 – IEC 61189-5-2:2015 © IEC 2015
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Accuracy, precision and resolution . 8
3.1 General . 8
3.2 Accuracy . 9
3.3 Precision . 9
3.4 Resolution . 10
3.5 Report. 10
3.6 Student’s t distribution . 10
3.7 Suggested uncertainty limits . 11
4 C: Chemical test methods . 12
4.1 Test 5-2C01: Corrosion, flux . 12
4.1.1 Object . 12
4.1.2 Test specimen . 12
4.1.3 Apparatus and reagents . 12
4.1.4 Procedures . 12
4.1.5 Additional information . 14
4.2 Test 5-2C02: Determination of acid value of liquid soldering flux
potentiometric and visual titration methods . 14
4.2.1 Object . 14
4.2.2 Test specimen . 14
4.2.3 Apparatus and reagents . 14
4.2.4 Procedures . 15
4.2.5 Additional information . 16
4.3 Test 5-2C03: Acid number of rosin . 16
4.4 Test 5-2C04: Determination of halides in fluxes, silver chromate method . 16
4.4.1 Object . 16
4.4.2 Test specimen . 17
4.4.3 Apparatus and reagents . 17
4.4.4 Procedure . 17
4.4.5 Evaluation . 17
4.4.6 Additional information . 17
4.5 Test 5-2C05: Solids content, flux . 18
4.5.1 Object . 18
4.5.2 Test specimen . 18
4.5.3 Apparatus and reagents . 18
4.5.4 Procedures . 19
4.5.5 Evaluation . 19
4.5.6 Additional information . 19
4.6 Test 5-2C06: Quantitative determination of halide content in fluxes (chloride
and bromide) . 19
4.6.1 Object . 19
4.6.2 Test specimen . 20
4.6.3 Apparatus and reagents . 20

4.6.4 Procedure . 21
4.6.5 Calculations . 22
4.6.6 Report . 23
4.6.7 Additional information . 23
4.7 Test 5-2C07: Qualitative analysis of fluorides and fluxes by spot test . 24
4.7.1 Object . 24
4.7.2 Test specimen . 24
4.7.3 Apparatus and reagents . 24
4.7.4 Procedure . 24
4.8 Test 5-2C08: Quantitative determination of fluoride concentration in fluxes . 24
4.8.1 Object . 24
4.8.2 Test specimen . 25
4.8.3 Apparatus and reagents . 25
4.8.4 Procedure . 25
4.8.5 Additional information . 27
4.8.6 Informative references . 27
4.9 Test 5-2C09: Specific gravity . 27
4.9.1 Object . 27
4.9.2 Test specimen . 27
4.9.3 Apparatus . 28
4.9.4 Test procedure . 28
4.9.5 Evaluation . 28
4.10 Test 5-2C10: Flux induced corrosion (copper mirror method) . 28
4.10.1 Object . 28
4.10.2 Test specimen . 28
4.10.3 Apparatus and reagents . 28
4.10.4 Procedure . 29
4.10.5 Evaluation . 29
4.10.6 Additional information . 30
4.10.7 Reference documents . 30
5 X: Miscellaneous test methods . 30
5.1 Test 5-2X01: Liquid flux activity, wetting balance method . 30
5.1.1 Object . 30
5.1.2 Test specimen . 30
5.1.3 Apparatus and reagents . 31
5.1.4 Procedure . 31
5.1.5 Evaluation . 31
5.1.6 Additional information . 31
5.2 Test 5-2X02: Spread test, liquid or extracted solder flux, solder paste and
extracted cored wires or preforms . 34
5.2.1 Object . 34
5.2.2 Method A . 34
5.2.3 Method B . 35
5.2.4 Additional information . 37
5.3 Test 5-2X03: Flux residues – Tackiness after drying . 37
5.3.1 Object . 37
5.3.2 Test specimen . 37
5.3.3 Apparatus and reagents . 37
5.3.4 Procedure . 38

– 4 – IEC 61189-5-2:2015 © IEC 2015
5.3.5 Evaluation . 39
5.3.6 Additional information . 39
Bibliography . 40

Figure 1 – Chlorides and/or bromides test results . 18
Figure 2 – Test equipment of specific gravity (hydrometer reading) . 28
Figure 3 – Flux type classification by copper mirror test . 30
Figure 4 – Wetting balance apparatus . 32
Figure 5 – Wetting balance curve . 33

Table 1 – Student’s t distribution . 11
Table 2 – Relation between halide content and mass of specimen . 22
Table 3 – Mixing ratio from specimen size to water quantity . 25
Table 4 – Specimen size to chloroform mixture . 26
Table 5 – Typical spread areas defined in mm . 35

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST METHODS FOR ELECTRICAL MATERIALS,
PRINTED BOARDS AND OTHER INTERCONNECTION
STRUCTURES AND ASSEMBLIES –
Part 5-2: General test methods for materials and assemblies –
Soldering flux for printed board assemblies

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61189-5-2 has been prepared by IEC technical committee 91:
Electronics assembly technology.
The text of this standard is based on the following documents:
FDIS Report on voting
91/1210/FDIS 91/1223/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 6 – IEC 61189-5-2:2015 © IEC 2015
This International Standard is used in conjunction with IEC 61189-1:1997, IEC 61189-2:2006,
IEC 61189-3:2007.
A list of all parts in the IEC 61189 series, published under the general title Test methods for
electrical materials, printed boards and other interconnection structures and assemblies, can
be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
IEC 61189 relates to test methods for materials or component robustness for printed board
assemblies, irrespective of their method of manufacture.
The standard is divided into separate parts, covering information for the designer and the test
methodology engineer or technician. Each part has a specific focus; methods are grouped
according to their application and numbered sequentially as they are developed and released.
In some instances test methods developed by other TCs (for example, TC 104) have been
reproduced from existing IEC standards in order to provide the reader with a comprehensive
set of test methods. When this situation occurs, it will be noted on the specific test method; if
the test method is reproduced with minor revisions, those paragraphs that are different are
identified.
This part of IEC 61189 contains test methods for evaluating robustness of materials or
component for printed board assemblies. The methods are self-contained, with sufficient
detail and description so as to achieve uniformity and reproducibility in the procedures and
test methodologies.
The tests shown in this standard are grouped according to the following principles:
P: preparation/conditioning methods
V: visual test methods
D: dimensional test methods
C: chemical test methods
M: mechanical test methods
E: electrical test methods
N: environmental test methods
X: miscellaneous test methods
To facilitate reference to the tests, to retain consistency of presentation, and to provide for
future expansion, each test is identified by a number (assigned sequentially) added to the
prefix (group code) letter showing the group to which the test method belongs.
The test method numbers have no significance with respect to an eventual test sequence; that
responsibility rests with the relevant specification that calls for the method being performed.
The relevant specification, in most instances, also describes pass/fail criteria.
The letter and number combinations are for reference purposes to be used by the relevant
specification. Thus "5-2C01" represents the first chemical test method described in
IEC 61189-5-2.
In short, in this example, 5-2 is the number of the part of IEC 61189, C is the group of
methods, and 01 is the test number.

– 8 – IEC 61189-5-2:2015 © IEC 2015
TEST METHODS FOR ELECTRICAL MATERIALS,
PRINTED BOARDS AND OTHER INTERCONNECTION
STRUCTURES AND ASSEMBLIES –
Part 5-2: General test methods for materials and assemblies –
Soldering flux for printed board assemblies

1 Scope
This part of IEC 61189 is a catalogue of test methods representing methodologies and
procedures that can be applied to test printed board assemblies.
This part of IEC 61189 focuses on test methods for soldering flux based on the existing
IEC 61189-5 and IEC 61189-6. In addition, it includes test methods of soldering flux for lead
free soldering.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61189-5, Test methods for electrical materials, interconnection structures and
assemblies – Part 5: Test methods for printed board assemblies
IEC 61189-6, Test methods for electrical materials, interconnection structures and
assemblies – Part 6: Test methods for materials used in manufacturing electronic assemblies
IEC 61190-1-1, Attachment materials for electronic assembly – Part 1-1: Requirements for
soldering fluxes for high-quality interconnections in electronics assembly
IEC 61190-1-3, Attachment materials for electronic assembly– Part 1-3: Requirements for
electronic grade solder alloys and fluxed and non-fluxed solid solders for electronic soldering
applications
ISO 9455 (all parts), Soft soldering fluxes – Test methods
ISO 9455-1, Soft soldering fluxes – Test methods – Part 1: Determination of non-volatile
matter, gravimetric method
ISO 9455-2, Soft soldering fluxes –Test methods – Part 2: Determination of non-volatile
matter, ebulliometric method
3 Accuracy, precision and resolution
3.1 General
Errors and uncertainties are inherent in all measurement processes. The information given
below enables valid estimates of the amount of error and uncertainty to be taken into account.
Test data serve a number of purposes which include

– monitoring of a process;
– enhancing of confidence in quality conformance;
– arbitration between customer and supplier.
In any of these circumstances, it is essential that confidence can be placed upon the test data
in terms of
– accuracy: calibration of the test instruments and/or system;
– precision: the repeatability and uncertainty of the measurement;
– resolution: the suitability of the test instrument and/or system.
3.2 Accuracy
The regime by which routine calibration of the test equipment is undertaken shall be clearly
stated in the quality documentation of the supplier or agency conducting the test and should
meet the requirements of ISO 9001.
The calibration shall be conducted by an agency having accreditation to a national or
international measurement standard institute. There should be an uninterrupted chain of
calibration to a national or international standard.
Where calibration to a national or international standard is not possible, round-robin
techniques may be used and documented to enhance confidence in measurement accuracy.
The calibration interval shall normally be one year. Equipment consistently found to be
outside acceptable limits of accuracy shall be subject to shortened calibration intervals.
Equipment consistently found to be well within acceptable limits may be subject to relaxed
calibration intervals.
A record of the calibration and maintenance history shall be maintained for each instrument.
These records should state the uncertainty of the calibration technique (in ± % deviation) in
order that uncertainties of measurement can be aggregated and determined.
A procedure shall be implemented to resolve any situation where an instrument is found to be
outside calibration limits.
3.3 Precision
The uncertainty budget of any measurement technique is made up of both systematic and
random uncertainties. All estimates shall be based upon a single confidence level, the
minimum being 95 %.
Systematic uncertainties are usually the predominant contributor and will include all
uncertainties not subject to random fluctuation. These include
– calibration uncertainties;
– errors due to the use of an instrument under conditions which differ from those under
which it was calibrated;
– errors in the graduation of a scale of an analogue meter (scale shape error).
Random uncertainties result from numerous sources but can be deduced from repeated
measurement of a standard item. Therefore, it is not necessary to isolate the individual
contributions. These may include
– random fluctuations such as those due to the variation of an influence parameter.
Typically, changes in atmospheric conditions reduce the repeatability of a measurement;

– 10 – IEC 61189-5-2:2015 © IEC 2015
– uncertainty in discrimination, such as setting a pointer to a fiducial mark or interpolating
between graduations on an analogue scale.
Aggregation of uncertainties: Geometric addition (root-sum-square) of uncertainties may be
used in most cases. Interpolation error is normally added separately and may be accepted as
being 20 % of the difference between the finest graduations of the scale of the instrument.
2 2
U = ± (U + U ) + U
t s r i
where
U is the total uncertainty;
t
U is the systematic uncertainty;
s
U is the random uncertainty;
r
U is the interpolation error.
i
Determination of random uncertainties: Random uncertainty can be determined by repeated
measurement of a parameter and subsequent statistical manipulation of the measured data.
The technique assumes that the data exhibits a normal (Gaussian) distribution.
t ×σ
U =
r
n
where
U is the random uncertainty;
r
n is the sample size;
t is the percentage point of the t distribution as shown in Table 1;
σ is the standard deviation (σ ).
n–1
3.4 Resolution
It is paramount that the test equipment used is capable of sufficient resolution. Measurement
systems used should be capable of resolving 10 % (or better) of the test limit tolerance.
It is accepted that some technologies will place a physical limitation upon resolution (for
example, optical resolution).
3.5 Report
In addition to requirements detailed in the test specification, the report shall detail
a) the test method used;
b) the identity of the sample(s);
c) the test instrumentation;
d) the specified limit(s);
e) an estimate of measurement uncertainty and resultant working limit(s) for the test;
f) the detailed test results;
g) the test date and operators’ signature.
3.6 Student’s t distribution
Table 1 gives values of the factor t for 95 % and 99 % confidence levels, as a function of the
number of measurements.
Table 1 – Student’s t distribution
Sample t value t value Sample t value t value
size 95 % 99 % size 95 % 99 %
2 12,7 63,7  14 2,16 3,01
3 4,3 9,92  15 2,14 2,98
4 3,18 5,84  16 2,13 2,95
5 2,78 4,6  17 2,12 2,92
6 2,57 4,03  18 2,11 2,9
7 2,45 3,71  19 2,1 2,88
8 2,36 3,5  20 2,09 2,86
9 2,31 3,36  21 2,08 2,83
10 2,26 3,25  22 2,075 2,82
11 2,23 3,17  23 2,07 2,81
12 2,2 3,11  24 2,065 2,8
13 2,18 3,05  25 2,06 2,79

3.7 Suggested uncertainty limits
The following target uncertainties are suggested:
a) Voltage < 1 kV: ± 1,5 %
b) Voltage > 1 kV: ± 2,5 %
c) Current < 20 A: ± 1,5 %
d) Current > 20 A: ± 2,5 %
Resistance
e) Earth and continuity: ± 10 %
f) Insulation: ± 10 %
g) Frequency: ± 0,2 %
Time
h) Interval < 60 s: ± 1 s
i) Interval > 60 s: ± 2 %
j) Mass < 10 g: ± 0,5 %
k) Mass 10 g – 100 g: ± 1 %
l) Mass > 100 g: ± 2 %
m) Force: ± 2 %
n) Dimension < 25 mm: ± 0,5 %
o) Dimension > 25 mm: ± 0,1 mm
p) Temperature < 100 °C: ± 1,5 %
q) Temperature > 100 °C: ± 3,5 %
r) Humidity 30 % to 75 % RH: ± 5 % RH
Plating thicknesses
s) Backscatter method: ± 10 %
t) Microsection: ± 2 µm
– 12 – IEC 61189-5-2:2015 © IEC 2015
u) Ionic contamination: ± 10 %
4 C: Chemical test methods
4.1 Test 5-2C01: Corrosion, flux
4.1.1 Object
This test method is designed to determine the corrosive properties of flux residues under
extreme environmental conditions. A pellet of solder is melted in contact with the test flux on a
sheet metal test piece. The solder is then exposed to prescribed conditions of humidity and
the resulting corrosion, if any, is assessed visually.
4.1.2 Test specimen
At least 0,035 g of flux solids, 1 g solder paste, 1 g wire, or 1 g preform with an equivalent
amount of solids. Flux solids are defined as the residue from the solid content, flux test
described in this 4.1. All solvent shall have been evaporated from the specimen in a chemical
fume hood.
4.1.3 Apparatus and reagents
The following apparatus and reagents are needed:
a) solder pot;
b) humidity chamber capable of achieving (40 ± 1) °C and (93 ± 2) % relative humidity;
c) air-circulating drying oven;
d) microscope having minimum 20×;
e) chemicals: All chemicals shall be reagent grade (highly pure, without contamination) and
water shall be distilled or deionized: ammonium persulphate; sulphuric acid, % volume
(v/v), degreasing agent; acetone, or petroleum ether;
f) analytical balance capable of weighing 0,001 g;
g) copper sheet of a thickness of (0,50 ± 0,05) mm and a purity of 99 %.
4.1.4 Procedures
4.1.4.1 Chemicals
a) Ammonium persulphate (25 % m/v in 0,5 % v/v sulphuric acid). Dissolve 250 g of
ammonium persulphate in water and add cautiously 5 ml of sulphuric acid (density
1,84 g/cm ). Mix, cool, dilute to 1 litre and mix. This solution should be freshly prepared.
b) Sulphuric acid (5 % v/v). To 400 ml of water cautiously add 50 ml of sulphuric acid
(density 1,84 g/cm ). Mix, cool, dilute to 1 l and mix.
4.1.4.2 Test panel preparation
a) Cut a piece of 50 mm × 50 mm from the copper sheet for each test.
b) Form a circular depression in the centre of each test panel 3 mm deep by forcing a steel
ball of a diameter of 20 mm into a hole of a diameter of 25 mm to form a cup.
c) Bend one corner of each test panel up to facilitate subsequent handling with tongs.
4.1.4.3 Preconditioning test panels
Immediately before performing the test, precondition as follows using clean tongs for handling.
a) Degrease with a suitable neutral organic solvent such as acetone or petroleum ether.
b) Immerse in 5 % sulphuric acid (by volume) at (65 ± 5) °C for 1 min to remove the tarnish
film.
c) Immerse in a solution of 25 % m/v ammonium persulphate (0,5 % v/v sulphuric acid) at
(23 ± 2) °C for 1 min to etch the surface uniformly.
d) Wash in running tap water for a maximum of 5 s.
e) Immerse in 5 % sulfuric acid (by volume) at (23 ± 2) °C for 1 min.
f) Wash for 5 s in running tap water, then rinse thoroughly in deionized water.
g) Rinse with acetone.
h) Allow to dry in clean air.
i) Use the test piece as soon as possible or store up to 1 h in a closed container.
4.1.4.4 Preparation of test solder
a) Weigh (1,00 ± 0,05) g specimen of solder for each test and place in the centre of
depression of each test panel.
b) Degrease solder specimen with a suitable neutral organic solvent such as acetone or
petroleum ether.
c) Solder may be in the form of pellets or by forming tight spirals of solder wire.
4.1.4.5 Test
a) Heat solder pot so that solder bath stabilizes at (235 ± 5) °C in the case of Sn63Pb37 and
o
Sn60Pb40 alloy, or at (255 ± 3) °C for Sn96,5Ag3Cu0,5, or at 35±3 C higher than the
liquidus temperature of any other solder alloy as agreed between the user and the
supplier. For solder alloys except Sn63Pb37 and Sn60Pb40, the temperature of the solder
pot may be approximately 40 °C higher than the liquid temperature of each alloy.
b) Liquid flux, place 0,035 g of flux solids into the depression in the test panel. Add solder
sample.
c) Solder paste, cored wire or cored preform, place 1 g of solder paste, flux-cored wire or
cored-preform into the depression in the test panel.
d) Using tongs, lower each test panel onto the surface of the molten solder.
e) Allow the test panel to remain in contact until the solder specimen in the depression of the
test panel melts. Maintain this condition for (5 ± 1) s.
f) Carefully examine the test panel at 20× magnification for subsequent comparison after
humidity exposure. Record observations, especially any discoloration.
g) Preheat test panel to (40 ± 1) °C for (30 ± 2) min.
h) Preset humidity chamber to (40 ± 1) °C and (93 ± 2) % relative humidity.
i) Suspend each test panel vertically (and separately) in the humidity chamber.
j) Expose panels to the above environment for 72 h (3 days). M (moderately active) and H
(highly active) flux may be tested in the cleaned, as well as uncleaned, condition.
4.1.4.6 Evaluation
Carefully examine test panels prior to placing them in the environmental chamber. Note any
discoloration.
After the appropriate exposure period, remove test panels from humidity chamber, examine at
20× magnification and compare with observations noted prior to exposure.
Corrosion is described as follows.
– Excrescences at the interfaces of the flux residue and copper boundary or the residues or
discontinuities in the residues.
– Discrete white or coloured spots in the flux residues.

– 14 – IEC 61189-5-2:2015 © IEC 2015
An initial change of colour which may develop when the test panel is heated during soldering
is disregarded, but subsequent development of green-blue discoloration with observation of
pitting of the copper panel is regarded as corrosion.
4.1.5 Additional information
4.1.5.1 Definition of corrosion
For the purposes of this test method, the following is the definition of corrosion: “chemical
reaction between the copper, the solder, and the constituents of the flux residues, which
occurs after soldering and during exposure to the above environmental conditions."
Colour photos before and after the test are valuable tools in identifying corrosion.
4.1.5.2 Safety
Observe all appropriate precautions on material safety data sheets (MSDS) for chemicals
involved in this test method.
4.2 Test 5-2C02: Determination of acid value of liquid soldering flux potentiometric
and visual titration methods
4.2.1 Object
This test method specifies two methods for the determination of the acid value of a flux of
types L, M or H.
Method A is a potentiometric titration method and is to be considered as the reference method.
Method B is an alternative, visual end-point, titration method.
See ISO 9455 for reference.
4.2.2 Test specimen
A minimum of 2,0 g of liquid flux, 10 g of solder paste, 150 g of cored wire or 10 g of solder
preforms.
4.2.3 Apparatus and reagents
4.2.3.1 General
a) Use only reagents of recognized analytical quality and only distilled or deionized water.
b) Ordinary laboratory apparatus.
c) The term “M” represents molarity of a solution and is calculated by taking the moles of
solute and dividing by the litres of solution, e.g. 1,00 mole of sucrose (about 342,3 g)
mixed into a litre of water equals 1,00 M (1,00 mol/l).
4.2.3.2 Potentiometric titration method (Method A)
a) Tetrabutyl ammonium hydroxide. 0,1 M (0,1 mol/l). Use a commercially available standard
solution or one prepared from a commercially available concentrated standard solution by
dilution with propan-2-ol. Standardize this solution against an accurately weighed amount
of benzoic acid (about 0,5 g) dissolved in dimethylformamide, previously neutralized to
thymol blue.
b) Propan-2-ol: neutralized with tetrabutyl ammonium hydroxide solution to a faint pink colour
using phenolphthalein as an indicator.
c) Ethanol 96% by volume: neutralized with tetrabutyl ammonium hydroxide solution to a
faint pink colour using phenolphthalein as an indicator.

d) Toluene: neutralized with tetrabutyl ammonium hydroxide solution to a faint pink colour
using phenolphthalein as an indicator.
e) Ethanol/toluene mixture: mix equal volumes of the ethanol 96 % by volume and toluene.
f) Millivoltmeter or pH meter.
g) Glass electrode.
h) Saturated calomel, or silver chloride/silver, electrode.
i) Magnetic or mechanical stirrer with variable speed drive.
4.2.3.3 Titration with visual end-point (Method B)
a) Ethanol 96 % by volume: neutralized with potassium hydroxide, 0,1 M in alcohol, to a faint
pink colour using phenolphthalein as an indicator.
b) Toluene: neutralized with potassium hydroxid
...