CONTROL, ANALYSIS, AND TESTING CHEMICAL ANALYSIS OF PLATING SOLUTIONS by Charles Rosenstein AM.254 Ltd., Ho/on, lsraei and Stanley Hirsch Leeam Consultants Ltd., New Rochelle, N. Y Plating solutions must be routinely analyzed in order to maintain the recommended bath formulation and to preempt the occurrence of problems related to improper levels of bath constituents. Contaminant levels in the solutions must also be monitored. Manufacturers of plating systems establish optimum specifications to ensure maximum solution efficiency and uniformity of deposits. The various factors that cause the concentrations of bath constituents to deviate from their optimum values are as follows: I. drag-out: 2. solution evaporation; 3. chemical decomposition; and 4. unequal anode and cathode efficiencies A current efficiency problem is recognized by gradual but continuous changes in pH, metal content, or cyanide content (see Table 1). The techniques employed for the quantitative analysis of plating solutions are classified as volumetric (titrimetric), gravimctric, and instrumental. Volumetric and grnvimetric methods are also known as “wet” methods. The analyst must select the method that is best suited and most cost effective for a particular application. The wet methods outlined here are simple, accurate, and rapid enough for practically all plating process control. They require only the common analytical equipment found in the laboratory, and the instructions are sufficiently detailed for an average technician to follow without any difficulty. The determination of small amounts of impurities and uncommon Table I. Problems Caused by Unequal Anode and Cathode Effkiencies High pH High anode efficiency Low pH High cathode efficiency High metal content High anode ctfiaency Low metal content High cathode eff~aency Hl:h fret cyamde Low anode efficiency Low free cyamde High anode efficiency 518
Transcript
CONTROL, ANALYSIS, AND TESTING
CHEMICAL ANALYSIS OF PLATING SOLUTIONS
by Charles Rosenstein AM.254 Ltd., Ho/on, lsraei
and Stanley Hirsch Leeam Consultants Ltd., New Rochelle, N. Y
Plating solutions must be routinely analyzed in order to maintain the recommended bath formulation and to preempt the occurrence of problems related to improper levels of bath constituents. Contaminant levels in the solutions must also be monitored. Manufacturers of plating systems establish optimum specifications to ensure maximum solution efficiency and uniformity of deposits. The various factors that cause the concentrations of bath constituents to deviate from their optimum values are as follows:
I. drag-out: 2. solution evaporation; 3. chemical decomposition; and 4. unequal anode and cathode efficiencies
A current efficiency problem is recognized by gradual but continuous changes in pH, metal content, or cyanide content (see Table 1).
The techniques employed for the quantitative analysis of plating solutions are classified as volumetric (titrimetric), gravimctric, and instrumental. Volumetric and grnvimetric methods are also known as “wet” methods. The analyst must select the method that is best suited and most cost effective for a particular application.
The wet methods outlined here are simple, accurate, and rapid enough for practically all plating process control. They require only the common analytical equipment found in the laboratory, and the instructions are sufficiently detailed for an average technician to follow without any difficulty. The determination of small amounts of impurities and uncommon
Table I. Problems Caused by Unequal Anode and Cathode Effkiencies
High pH High anode efficiency Low pH High cathode efficiency High metal content High anode ctfiaency Low metal content High cathode eff~aency Hl:h fret cyamde Low anode efficiency Low free cyamde High anode efficiency
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metals should be referred to a competent laboratory, as a high degree of skill and chemical knowledge are required for the determination of these constituents.
Hull cell testing (see the section on plating cells elsewhere in this Guidehook) enables the operator to observe the quality of a deposit over a wide current density range.
VOLUMETRIC METHODS
When titrants composed of standard solutions are added to a sample that contains a component whose concentration is to be quantrtatively determined, the method is referred to as a volumetric method. The component to be determined must react completely with the titrant in stoichiometric proportions. From the volume of titrant required, the component’s concentration is calculated. The simplicity, quickness, and relatrvely low cost of volumetric methods make them the most widely used for the analysis of plating and related solutrons.
Volumetric methods involve reactions of several types: oxidation-reduction, acid-base, complexation, and precipitation. Indicators are auxiliary reagents, which usually signify the endpoint of the analysis. The endpoint can be indicated by a color change, formation of a turbid solution, or the solubilization of a turbid solution.
Some volumetric methods require little sample preparation, whereas others may require extensive preparation. Accuracy decreases for volumetric analyses of components found in low concentrations, as endpoints are not as easily observed as with the components found in high concentrations.
Volumetric methods are limited in that several conditions must be satisfied. Indicators should be available to signal the endpoint of the titration. The component-trtrant reaction should not be affected by interferences from other substances found in the solution.
GRAVIMETRIC METHODS
In gravimetric methods, the component being determined is separated from other components of the sample by precipitatron, volatilir.ation, or electroanalytical means. Precipitation methods are the most rmportant gravimetnc methods. The precipitate is uquallq a very slightly coluble compound of high purity that contains the component. The weight of the precipitate is determined after it is filtered from solution, washed, and dried. Gravimetric methods are used to supplement the available volumctrlc methods.
Limitations of gravimetric methods include the requirement that the precipitated component has an extremely low solubihty. The precipitate must al\o be of high purity and be easily filterable.
Species that are analyzed gravimetrically include chloride, sulfate, carbonate, phosphate, gold, and silver.
INSTRUMENTAL METHODS
Instrumental methods differ from wet methods in that they measure a physical property related to the composition of a rubstance, u herear wet methods rely on chemical reactmns. The selection of an instrument for the analysis of plating solutions 15 a difficult task. Analysts must decide if the cost is justified and if the analytical instrument is capable of analyzing for the required substances with a high degree of accuracy and precision. Instruments coupled to computers can automatically sample, analyze, and record results. Mathematical errors are minimized and sample measurements are more reproducible than with wet methods. Instrumental methods are also extremely rapid when compared with wet method<.
Unlike humans, instruments cannot judge. They cannot recognire improper sample preparation or interfering substances. Erroneous results are sometimes produced by electronic and mechanical malfunctions.
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Analytical instruments frequently used in the analysis of plating solutions can be categorized as spectroscopic. photometric, chromatographic, and electroanalytical. Spectro- scopic methods (flame photometry, emission spectrometry, X-ray fluorescence, mass spec- trometry. and inductively coupled plasma) are based on the emission of light. Photometric methods (spectrophotometry, calorimetry, and atomic absorption) are based on the absorption of light. Chromatographic methods (ion chromatography) involve the separation of substance\ for subsequent identification. Electroanalytical methods (potentiometry. conductometry, polarography, amperometry. and electrogravimetry) involve an electric current in the course of the analysis.
The instrumental methods. comprehensively reviewed below. are most applicable to plating environments.
SPECTROSCOPIC METHODS
Spectroscopy is the analysis of a substance by the measurement of emitted light. When heat. electrical energy, or radiant energy is added to an atom, the atom becomes excited and emits light. Excitation can be caused by a flame. spark, X-rays, or an AC or DC arc. The electrons in the atom are activated from their ground state to unstable energy shells of higher potential energy. Upon returning to their ground state, energy is released in the form of electromagnetic radiation.
Because each element contains atoms with different arrangements of outermost elec- trons, a distinct set of wavelengths is obtained. These wavelengths, from atoms of several elements, are separated by a monochromator such as a prism or a diffraction grating. Detection of the wavelengths can be accomplished photographically (spectrograph) or via direct-reading photoelectric detectors (spectrophotometers). The measurement of intensity emitted at a particular wavelength is proportional to the concentration of the element being analyzed.
An advantage of spectroscopy is that the method is specific for the element being analyzed. It permits quantitative analysis of trace elements without any preliminary treatment and without prior knowledge as to the presence of the element. Most metals and \ome nonmetals may be analyzed. Spectroscopic analysis is also useful for repetitive analytical work.
Disadvantages of spectroscopic analysis include the temperature dependence of intensity measurements, as intensity is very sensitive to small fluctuations in temperature. The accuracy and precision of spectrographic methods is not as high as some spectrophotometric methods or wet analyses. Spectrographic methods are usually limited to maximum element concen- trations of 3%. Additionally, semitivity is much smaller for elements of high energy (e.g.. zinc) than for elements of low energy (e.g., sodium).
Applications of spectroscopy include the analysis of major constituent!, and impurities in plating solutions, and of alloy deposits for composition.
Flame Photometry In flame photometry (FP), a sample in solution is atomized at constant air pressure and
introduced in its entirety into a flame as a fine mist. The temperature of the flame (1,800-3,100-K) is kept constant. The solvent is evaporated and the solid is vaporized and then dissociated into ground state atoms. The valence electrons of the ground state atoms are excited by the energy of the flame to higher energy levels and then fall back to the ground state. The intenhitie\ of the emitted spectrum lines are determined in the spectrograph or measured directly by a spectrophotometer.
The flame photometer is calibrated with standards of known composition and concen- tration. The intensity of a given spectral line of an unknown can then be correlated with the amount of an element present that emits the specific radiation.
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Physical interferences may occur from solute or solvent effects on the rate of transport of the sample into the flame. Spectral interferences are caused by adjacent line emissions when the element being analyzed has nearly the same wavelength as another element. Monochromators or the selection of other spectral lines minimiLe this interference. Ionization interferences may occur with the higher temperature flames. By adding a second ionizable element, the interference< due to the ionization of the element being determined are minimized.
An advantage of FP IS that the temperature of the flame can be kept more nearly constant than with electric sources. A disadvantage of the method is that the sensitivity of the flame wurce is many times smaller than that of an electric arc or cpark.
FP is used for the analysis of aluminum, boron, cadmium, calcmm, chromium, cobalt, copper, indium, Iron, lead, lithium, magnesium, nickel, palladium, platinum, potassium. rhodium, ruthenium, silver, sodium, strontium, tin, and rinc.
Emission Spectrometry In emission spectrometry (ES), a sample composed of a solid, cast metal or solution 1s
ewclted by an electric discharge such as an AC arc, a DC arc, or a spark. The sample is usually placed in the cavity of a lower graphite electrode, which 15 made positiv-e. The upper counterelectrode is another graphite electrode ground to a point. Graphite is the preferred electrode material because of Its abihty to withstand the high electric discharge temperatures. It is also a good electrical conductor and does not generate its own spectral lines.
The arc is started by touching the two graphite electrodes and then separating them The extremely high temperatures (J,OOGh,OOO“K) produce emitted radiation higher in energy and in the number of spectral lines than in flame photometry. Characteristic wavelengths from atoms of several elements arc separated by a monochromator and are detected hy \pectro- graphs or ?pectrophotometers. Qualitative identifuxtion i\ performed by using available charts and tables to identify the \pectrnl lines that rhe emission spectrometer sorts out according to their wavelength. The elements present in a rample can alw he quahtatlcrly determined by comparmg the spectrum of an unknown wnh that of pure samples of the elements. The density of the wakelengths is proportional to the concenwatwn of the clement being determined. Calibrations are done against standard samples.
ES is a useful method for the analysis of trdce metallic contdmmantr in plating barhu. Ihe “oxide” method is a common quantitative technique in ES. A sample of the plating bath is evaporated to dryness and then heated rn a muffle fwnace. The resultant oxides are mixed with graphite and placed in a praphlte electrode. Stand,wds are Gmilarly prepared dnd a I)( drc i5 used to excite the sample and Gandards.
X-ray Fluorescence X-ray fluorescence o(N) qwctrosc~~py is baaed on the cxcltatlon of wnpler hq an
X-ray source of sufficiently high energy, resulting in the cmi<>ion of Iluorcsccnt r.ldiatmn. lhe concentration of the element being determined IS proportional to the intsnsit> of ItS chartcterihtic N avelength. A I) pical XRF q)ectrometcr consists of an X-ray ~owcc. ;I detector, and a data analyzer.
Advantagr~ of XRF include the nondestructive nature *If the X-ray\ on the tample. XRF is useful in measuring the major constituents of platrng baths wch ;I- cadmium. chrommm. cobalt, gold, nickel, silver, tin, and lint. I>~~ad\:cnta~es of ?rRF ~ncludc its lack of wn\itl\tt) as compared with ES.
X-ray spectroscopy ih alw used to measure the thichnetr of a plated deposit. ‘The X-ray detector is placed on the wavelength of the element bring meawred. rhe surface of the deposit is exposed to an X-ray source and the intensity of the element ~a\rlrngth is measured. A calibration cur\e is cowtructed for intensity against thickness for a particular deposit. Coating compositions can also be determined by XRF.
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Mass Spectrometry In mass spectrometry (MS), gases or vapors derived from liquids or solids are bombarded
by a beam of electrons in an ionization chamber, causing ionization and a rupture of chemical bonds. Charged particles are formed, which may be composed of elements, molecules, or fragments. Electric and magnetic fields then separate the ions according to their mass to charge ratios (m/r). The amount and type of fragments produced in an ionization chamber. for a particular energy of the bombarding beam, are characteristic of the molecule; therefore, every chemical compound has a distinct mass spectrum. By establishing a mass spectrum of several pure compounds, an observed pattern allows identification and analysis of complex mixtures.
The mass spectrum of a compound contains the masses of the ion fragments and the relative abundances of these ions plus the parent ion. Dissociation fragments will always occur in the came relative abundance for a particular compound.
MS is applicable to all substances that have a sufficiently high vapor pressure. This usually includes substances whose boiling point is below 450°C. MS permits qualitative and quantitative analysis of liquids, solids, and gases.
Inductively Coupled Plasma Inductively coupled plasma (ICP) involves the aspiration of a sample in a stream of
argon gas, and then its ionization by an applied radio frequency field. The field is inductively coupled to the ionized gas by a coil surrounding a quartz torch that supports and encloses the plasma. The sample aerosol is heated in the plasma, the molecules become almost completely dissociated and then the atoms present in the sample emit light at their characteristic frequencies. The light passes through a monochromator and onto a detector.
The high temperature (7,OOO”K) of the argon plasma gas produces efficient atomic emission and permits low detection limits for many elements. As with atomic absorption (AA), ICP does not distinguish between oxidation states (e.g., Cr” and Crhi) of the same element-the total element present is determined. Advantages of ICP include complete ionization and no matrix interferences as in AA. ICP allows simultaneous analysis of many elements in a short time. It is sensitive to part-per-billion levels.
Disadvantages of ICP include its high cost and its intolerance to samples with greater than 3% dissolved solids. Background corrections usually compensate for interferences due to background radiation from other elements and the plasma gases. Physical interferences, due to viscosity or surface tension, can cause significant errors. These errors are reduced by diluting the sample. Although chemical interferences are insignificant in the ICP method, they can be greatly minimized by careful selection of the instrument’s operating conditions. by matrix matching, or by buffering the sample.
ICP is applicable to the analysis of major components and trace contaminant, in plating solutions. It is also useful for waste-treatment analysis.
PHOTOMETRIC METHODS
Photometric methods are based on the absorption of ultraviolet (200-400 nm) or visible (400-1,000 nm) radiant energy by a species in solution. The amount of energy absorbed is proportional to the concentration of the absorbing species in solution. Absorption is determined spectrophotometrically or calorimetrically.
The sensitivity and accuracy of photometric methods must be frequently checked by testing standard solutions in order to detect electrical, optical, or mechanical malfunctions in the analytical instrument.
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Spectrophotometry and Colorimetry
S~~e~rropllotonzer~~ involves analysis by the measurement of the light absorbed by a solution. The absorbance is proportional to the concentration of the analyte in solution. Spectrophotometric methods are most often used for the analysis of metals with concentra- tions of up to 2%.
Spectrophotometers consist of a light source (tungsten or hydrogen), a monochromator, a sample holder, and a detector, Ultraviolet or vjisible light of a definite wavelength is used as the light source. Detectors are photoelectric cells that measure the transmitted (unabsorbed) light, Spectrophotometers differ from photometers in that they utilirc monochromators. whereas photometers use filters to isolate the desired wavelength region. Filter\ isolate a wider band of light.
In spectrophotometric titrations, the cell containing the analyte solution is placed in the light path of a spectrophotometer. Titrant is added to the cell with stirring. and the absorbance is measured. The endpoint is determined graphically. Applications of this titration include the analysis of a mixture of arsenic and antimony and the analysis of copper with ethylene diamine tetra acetic acid (EDTA).
The possibihty of errors in spectrophotometric analyses is increased when numerous dilutions are required for an analysis.
Colorirner~~ involves comparing the color produced by an unknown quantity of a substance with the color produced by a standard containing a known quantity of that substance. When monochromatic light passes through the colored solution, a certain amount of the light, proportional to the concentration of the substance, will be absorbed. Substances that are colorless or only slightly colored can he rendered highly colored by a reaction with special reagents.
In the standard series calorimetric method. the analytc solution is diluted to a certain volume (usually 50 or I00 ml) in a Ncsslcr tube and mixed. The color of the solution is compared with a series of standards similarly prepared. The concentration of the analyte equals the concentration of the standard solution whose color it matches exactly. Colors can also be compared to standards via a colorimctcr (photometer), comparator. or apcctropho- tometer.
The possible errors in calorimetric measurements may arise from the following sources: turbidity, sensitivity of the eye or color blindness, dilutions. photometer filter\. chemical interferences, and variation\ in temperature or pH.
Photometric methods arc available for the analysis of the following analytes:
Anodizing solutions: Fe, Cu. Mn Brass solutions: Fe Cadmium solutions: Fe, Ti. Zn. Cu. Ni Chromium solutions: Cr, Fe, Ni, Cu, SC Acid copper solutions: Cl, Fe Alkaline copper solutions: Fe, Se Gold solutions: Au. Ni, In, Co. Cu, Fe, PO, Iron solutions: Mn, NH, Lead and tin-lead solutions: Pb Nickel solutions: Cr. Cu. Zn, Fe. Co, NH, Palladium solutions: Pd. Cr. NH, Platinum solutions: Pt Rhodium solutions: Rh Silver solutions: Ni. Cu. Sb Acid tin solutions: Fe. Cu Alkaline tin solution\: Cu. Pb, Zn
Atomic Absorption Metals in plating and related solutions can be readily determined by AA spectropho-
tometry. Optimum ranges, detection limits, and sensitivities of metals vary with the various available instruments.
In dire&os@rrtiort atontic crb.sor/,tiort (DAAA) analysis, the flame (usually air- acetylene or nitrous oxide-acetylene) converts the sample aerosol into atomic vapor. which absorbs radiation from a light source. A light source from a hollow cathode lamp or an electrodeless discharge lamp is used, which emits a spectrum specific to the element being determined. The high cost of these lamps is a disadvantage of the AA method. A detector measures the light intensity to give a quantitative determination.
DAAA is similar to flame photometry in that a sample is aspirated into a flame and atomized. The difference between the two methods is that tlame photometry measures the amount of emitted light. whereas DAAA measures the amount of light absorbed by the atomized element in the flame. In DAAA. the number of atoms in the ground state is much greater than the number of atoms in any of the excited states of the spectroscopic methods. Consequently, DAAA is more efficient and has better detection limits than the spectroscopic methods.
Spectral interferences occur when a wavelength of an element being analyzed is close to that of an interfering element. The analysis will result in an erroneously high measurement. To compensate for this interference, an alternate wavelength or smaller slit width is used.
When the physical properties (e.g.. viscosity) of a sample differ from those of the standard, matrix interferences occur. Absorption can be enhanced or suppressed. To overcome these interferences, matrix components in the sample and standard are matched or a release agent, such as EDTA or lanthanum, is added.
Chemical interferences are the most common interferences encountered in AA analysis. They result from the nonabsorption of molecularly bound atoms in the flame. These interferences are minimized by using a nitrous oxide-acetylene flame instead of an air-acetylene flame to obtain the higher flame temperature needed to dissociate the molecule or by adding a specific substance (e.g., lanthanum) to render the interferant harmless. Chemical interferences can also be overcome by extracting the element being determined or by extracting the interferant from the sample.
The sensitivity and detection limits in AA methods vary with the instrument used, the nature of the matrix, the type of element being analyzed, and the particular AA technique chosen. It is best to use concentrations of standards and samples within the optimum concentration range of the AA instrument. When DAAA provides inadequate sensitivity. other specialized AA methods, such as graphite fur-nace AA, cold vapor AA, or hydride AA. are used.
In ~rr@n’tr furnace AA (GFAA). the flame that is used in DAAA is replaced w’ith an electrically heated graphite furnace. A solution of the analyte is placed in a graphite tube in the furnace, evaporated to dryness, charred, and atomized. The metal atoms being analyzed are propelled into the path of the radiation beam by increasing the temperature of the furnace and causing the sample to bc volatilized. Only very small amounts of sample are required for the analysis.
GFAA is a very sensitive technique and permits very low detection limits. The increased sensitivity is due to the much greater occupancy time of the ground state atoms in the optical path as compared with DAAA. Increased sensitivity can also be obtained by using larger sample volumes or by using an argon-hydrogen purge gas mixture instead of nitrogen, Because of its extreme sensitivity. determining the optimum heating times. temperature. and matrix modifiers is necessary to overcome possible interferences.
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Interferences may occur in GFAA analysis due to molecular absorption and chemical effects. Background corrections compensate for the molecular absorption interference. Specially coated graphite tubes minimize its interaction with some elements. Gradual heating helps to decrease background interference, and permits determination of samples with complex mixtures of matrix components.
The GFAA method has been applied to the analysis of aluminum, antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, selenium, silver, and tin.
Cold vapor atomic absorprion (CVAA) involves the chemical reduction of mercury or selenium by stannous chloride and its subsequent analysis. The reduced solution is vigorously stirred in the reaction vessel to obtain an equilibrium between the element in the liquid and vapor phases. The vapor is then purged into an absorption cell located in the light path of a spectrophotometer. The resultant absorbance peak is recorded on a strip chart recorder.
The extremely sensitive CVAA procedure is subject to interferences from some organics, sulfur compounds, and chlorine. Metallic ions (e.g., gold, selenium), which are reduced to the elemental state by stannous chloride, produce interferences if they combine with mercury.
Hydride atomic absorpfion (HAA) is based on chemical reduction with sodium borohydride to selectively separate hydride-forming elements from a sample. The gaseous hydride that is generated is collected in a reservoir attached to a generation flask, and is then purged by a stream of argon or nitrogen into an argon-hydrogen-air flame. This permits high-sensitivity determinations of antimony, arsenic, bismuth, germanium, selenium, tellu- rium, and tin.
The HAA technique is sensitive to interferences from easily reduced metals such as silver, copper, and mercury. Interferences also arise from transition metals in concentrations greater than 200 mg/L and from oxides of nitrogen.
Ion Chromatography In ion chromatography (IC), analytes are separated with an eluent on a chromatographic
column based on their ionic charges. Because plating solutions are water based, the soluble components must be polar or ionic; therefore, IC is applicable to the analysis of plating and related solutions.
Ion chromatographs consist of a sample delivery system, a chromatographic separation column, a detection system, and a data handling system.
IC permits the rapid sequential analysis of multiple analytes in one sample. The various detectors available, such as W-visible, electrochemical, or conductivity, allow for specific detection in the presence of other analytes. IC is suitable for the analysis of metals, anionic and cationic inorganic bath constituents, and various organic plating bath additives. It is also used for continuous on-line operations.
Interferences arise from substances that have retention times coinciding with that of any anion being analyzed. A high concentration of a particular ion may interfere with the resolution of other ions. These interferences can be greatly minimized by gradient elution or sample dilution.
IC has been applied to the analysis of the following analytes in plating and related solutions:
Electroanalytical methods involve the use of one or more of three electrical quantities+urrent, voltage, and resistance. These methods are useful when indicators for a titration are unavailable or unsuitable. Although trace analysis may be done quite well by spectroscopic or photometric methods, electroanalytical methods offer ease of operation and relatively lower costs of purchase and maintenance.
Potentiometry Potentiometry involves an electrode that responds to the activity of a particular group of
ions in solution. Potentiometric methods correlate the activity of an ion with its concentration in solution.
In potentiometric titrations, titrant is added lo a solution and the potential between an indicator and reference electrode is measured, The reaction must involve the addition or removal of an ion for which an electrode is available. Acid-base titrations are performed with a glass indicator electrode and a calomel reference electrode. The endpoint corresponds to the maximum rate of change of potential per unit volume of titrant added.
Advantages of potentiometric titration5 include irs applicability to colored. turbid, or fluorescent solutions. It is also useful in situations where indicators are unavailable.
The sensitivity of potentiometric titrations is limited by the accuracy of the measuxment of electrode potentials at low concentrations. Solutions that arc more dilute than 10 ’ N cannot be accurately titrated potentiometrically. This is because the experimentally measured electrode potential is a combined potential. which may differ appreciably from the true electrode potential. The difference between the true and experimental electrode potentials ia due to the residual current. which arises from the presence of electroactive trace impurities.
The direct potentiometric measurement of single ion concentrations is done with ion selective electrodes (ISEa). The ISE develops an electric potential in response to the activity of the ion for which the electrode is specific. ISEs are available for measuring calcium, copper, lead, cadmium, ammonia, bromide, nitrate, cyanide, sulfate, chloride, fluoride, and other cations and anions.
Cation ISEs encounter interferences from other cations, and anion ISEs encounter interferences from other anions. Theae interferences can be eliminated by adjusting the sample pH or by chelating the interfering ions. ISE instructions must be reviewed carefully to determine the maximum allowable levels of interferants, the upper limit of the single ion concentration for the ISE, and the type of media compatible with the particular ISE.
Some of the solutions that can be analyzed by potentiometric methods are:
Conductometry Electrolytic conductivity measures a solution’s ability to carry an electric current. A
current is produced by applying a potential between two inert metallic electrodes (e.g., platinum) inserted into the solution being tested. When other variables are held constant, changes in the concentration of an electrolyte result in changes in the conductance of electric current by a solution.
In conductometric titrations, the endpoint of the titration is obtained from a plot of conductance against the volume of titrant. Excessive amounts of extraneous foreign electrolytes can adversely affect the accuracy of a conductometric titration.
Conductometric methods are used when wet or potentiometric methods give inaccurate results due to increased solubility (in precipitation reactions) or hydrolysis at the equivalence point. The methods are accurate in both dilute and concentrated solutions, and they can also be u5ed with colored solutions.
Conductometric methods have been applied to the analysis of Cr. Cd, Co, Fe, Ni, Pb, Ag, Zn, CO,, Cl, F, and SO,.
Polarography In polarography, varying voltage is applied to a cell consisting of a large mercury anode
(reference electrode) and a small mercury cathode (indicator electrode) known as a dropping mercury electrode (DME). Consequent changes in current are measured. The large area of the mercury anode precludes any polarization. The DME consists of a mercury reservoir attached to a glass capillary tube with small mercury drops falling slowly from the opening of the tube. A saturated calomel electrode is sometimes used as the reference electrode.
The electrolyte in the cell consists of a dilute solution of the species being determined in a medium of supporting electrolyte. The supporting electrolyte functions to carry the current in order to raise the conductivity of the solution. This ensures that if the species to be determined is charged, it will not migrate to the DME. Bubbling an inert gas, such as nitrogen or hydrogen, through the solution prior to running a polarogram, will expel dissolved oxygen in order to prevent the dissolved oxygen from appearing on the polarogram.
Reducible ions diffuse to the DME. As the applied voltage increases, negligible current flow results until the decomposition potential is reached for the metal ion being determined. When the ions are reduced at the same rate as they diffuse to the DME, no further increases in current occur, as the current is limited by the diffusion rate. The half-wave potential is the potential at which the current is 50% of the limiting value.
Polarograms are obtained by the measurement of current as a function of applied potential. Half-wave potentials are characteristic of particular substances under specified conditions. The limiting current is proportional to the concentration of the substance being reduced. Substances can be analyzed quantitatively and qualitatively if they are capable of undergoing anodic oxidation or cathodic reduction. As with other instrumental methods, results are referred to standards in order to quantitate the method.
Advantages of polarographic methods include their ability to permit simultaneous qualitative and quantitative determinations of two or more analytes in the same solution. Polarography has wide applicability to inorganic, organic, ionic, or molecular species.
Disadvantages of polarography include the interferences caused by large concentrations of electropositive metals in the determination of low concentrations of electronegative metals. The very narrow capillary of the DME occasionally becomes clogged.
Polarographic methods are available for the following solutions:
Chromium solutions: Cu, Ni, Zn, Cl, SO, Acid copper solutions: Cu. Cl Alkaline copper solutions: Zn, Fe, Pb, Cu Gold solutions: Au, Cu, Ni, Zn, In, Co, Cd Iron solutions: Mn Lead and tin-lead solutions: Cu, Cd, Ni, ‘Zn, Sb Nickel solutions: Cu. Pb, Zn, Cd, Na, Co, Cr, Mn Palladium solutions: Pd, Cr” , CT”+ Rhodium solutions: Rh Silver solutions: Sb, Cu, Cd Acid tin solutions: Sn4+, Cu, Ni, Zn Alkaline tin solutions: Pb, Cd, Zn, Cu Acid zinc solutions: Cu. Fe, Pb, Cd Alkaline zinc solutions: Pb. Cd, Cu Wastewater: Cd Cu Cr’+, Ni, Sn, Zn 1 3
Amperometry Amperometric titrations involve the use of polarography as the basis of an electrometric
titration. Voltage applied across the indicator electrode (e.g., DME or platinum) and reference electrode (e.g., calomel or mercury) is held constant and the current passing through the cell is measured as a function of titrant volume added. The endpoint of the titration is determined from the intersection of the two straight lines in a plot of current against volume of titrant added. Polarograms are run to determine the optimum titration voltage.
Amperometric titrations can be carried out at low analyte concentrations at which volumetric or potentiometric methods cannot yield accurate results. They are temperature independent and more accurate than polarographic methods. Although amperometry is useful for oxidation-reduction or precipitation reactions, few acid-base reactions are determined by this method.
Some of the reactions that can be analyzed by amperometric methods are given in Table II.
Electrogravimetry In electrogravimetry, the substance to be determined is separated at a fixed potential on
a preweighed inert cathode, which is then washed, dried. and weighed. Requirements for an accurate electrogravimetric analysis include good agitation, smooth adherent deposits, and proper pH, temperature, and current density.
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Table III. Molarities and Normalities of Standard Solutions
Advantages of electrogravimetry include its ability to remove quantitatively most common metals from solution. The method does not require constant supervision. Disadvan- tages include long electrolysis times.
Some of the metals that have been determined clectrogravimetrically are cadmium. cobalt, copper. gold, iron. lead. nickel, rhodium, silver. tin, and zinc.
SAMPLING
Analyses are accurate only when the sample is truly representative of the solution being analyzed. Each tank should have a reference mark indicating the correct level for the solution, and the bath should always be at this level when the sample is taken. Solutions should be stirred before sampling. If there is sludge in the tank. the solution should be stirred at the end of the day and the bath allowed to stand overnight, taking the sample in the morning.
Solutions should be sampled by means of a long glass tube. The tube is immersed in the solution, the thumb is placed over the upper open end. and a full tube of solution is withdrawn and transferred to a clean, dry container. The solution should be sampled at a minimum of IO locations in the tank to ensure a representative sample. A quart sample is sufficient for analysis and Hull cell testin g, and any remaining solution can be returned to its tank.
STANDARD SOLUTIONS, REAGENTS, AND INDICATORS FOR WET METHODS
Standard solutions, reagents, and indicators can be purchased ready-made from labora- tory supply distributors. Unless a laboratory has the experience and high degree of accuracy that is required in preparing these solutions, it is recommended that they be purchased as prepared solutions. Preparations for all the solutions are given here to enable technicians to prepare or recheck their solution?.
A standard solution is a solution with an accurately known concentration of a substance used in a volumetric analysis. Standardiration of standard solutions requires greater accuracy than routine volumetric analyses. An error in standardization causes errors in all analyses that are made with the solution: therefore. Primary Standard Grade chemicals should be used to standardize standard solutions.
The strengths of standard solutions are usually expressed in terms of normality or molarity. Normalities of standard solutions and their equivalent molarities are listed in Table III. The methods to standardize all the standard solutions required for the analysis of plating and related solutions are listed in Table IV.
532
Indicators are added to solutions in volumetric analyses to show color change or onset of turbidity, signifying the endpoint of a titration. The indicators required for all of the analyses and their preparations are listed in Table V. Analytical Grade chemicals should be used in preparing analytical reagents (Table VI) and Reagent Grade acids should be used (Table VII). When chemicals of lesser purity are used, the accuracy of the results will be diminished.
Tables VIII through XII provide specific methods for testing the constituents of electroplating. electroless. and anodizing baths, as well as acid dips and alkaline cleaners.
SAFETY
As with any laboratory procedure, the accepted safety rules for handling acids, bases, and other solutions should be followed. Acids are always added to water. not the reverse. Mouth pipettes should not be used for pipetting plating solutions. Safety glasses should always be worn, and care should be exercised to avoid skin and eye contact when handling chemicals. A fume hood should be used when an analytical method involves the liberation of harardoua or annoying fumes. Laboratory staff should be well versed in the fir&t-aid procedures required for various chemical accidents.
DETERMINATION OF CATHODE EFFICIENCY
The procedure for determining cathode efficiency, using the setup pictured in Fig. I, is as follows:
I. Connect the copper coulometer in series with the test cell. 2. The copper coulometer solution should contain 30 or/gal copper sulfate pentahydrate
and 8 oz/gal sulfuric acid. 3. Use the same anodes, temperature, and agitation in the test solution that are used in
the plating bath. 4. Plate at 0.4 A (30 A/ft’) for a minimum of IO minutes. 5. Rinse both cathodes, dry in acetone, and weigh.
weight in gram5 of test metal X valence of test metal in bath X 3177 Ic Cathode Efficiency =
weight in grams of copper metal X atomic weight of test metal
Test Solution Copper Coulometer
Tabl
e IV
. St
anda
rdiz
atio
n of
Sta
ndar
d So
lutio
ns
Solu
/io~i
0.1
M
ED
TA
37.0
B
Nal
EDTA
.2H
,0
per
liter
H
,O
0.1
N H
CI
Y m
l 36
%
HC
I pe
r bt
er
H,O
1.
0 N
H
CI
X9
1111
36%
H
CI
per
Rer
r~c”
” (T
o he
rrd
dd
,,I o
t-ckr
li,
\r~d)
5.0
8 C
CO
, di
rwlv
ed
m
I:3
HC
I an
d di
lute
d tu
500
m
l in
a
volu
met
ric
tlask
. P
ipet
te
20.m
l ra
mpl
e,
add
100
ml
H,O
, *’
IO
m
l pH
IO
huf
ferfe
r. and
EBT
po
wder
.
0.2
0” N
a2C
0,.
I25
ml
H,O
. an
d br
omoc
reso
l gr
een.
2 0
g N
a,C
O,.
I25
ml
H,O
, an
d br
orno
cres
ol
gree
n.
liter
H,O
0.
1 N
I,
12.7
g l
l. 24
.0
g K
I pe
r lit
er
H,O
0.01
N
H
g(N
O&
I.0
83
g H
pO.
5 m
l 50
%
HN
O,
per
liter
HJ
I 0.
1 N
K
I-KIO
, 3.
6 g
KIO
,. I.0
g
NaO
H,
IO.0
g
KI
per
hter
H
z0
0 2
g A
s20q
, 20
ml
I .O
N N
aOH
, ge
ntly
he
at u
ntd
As,
O,
diaw
lves
, co
ol,
add
phen
olph
thal
ein.
I.0
N
H
CI
adde
d fro
m
pink
to
col
orle
ss.
100
ml
H1O
. I
ml
cont
. H
Cl.
2 2
hica
rhon
ate
adde
d sl
owly
, an
d st
arch
w
lutm
n.
7.5
g K
CI
disw
lwxi
in
Hz0
an
d dd
utrd
to
I.0
00
ml
m a
vol
umet
ric
f&k.
P
ipet
te
2.m
l sa
mpl
e,
add
100
ml
H,O
, an
d I5
m
l 20
%
trich
lonx
lcet
ic
actd
.
In S
Wm
l fla
sk
add
0.20
g
Sn.
I0
0 m
l co
ne
HC
I, 2
drop
\ S
bCI,
wlu
tion.
le
t st
and
at r
oom
te
mpe
ratu
re
1111
diw
Tlve
d.
Add
I8
0 m
l H
,O,
j-in
fold
ed
“U-s
hape
d ni
ckel
\tr
~p.
and
5.0
g re
duce
d iro
n po
wde
r S
lopp
er
lla\k
w
th
rubb
er
wpp
er
fitte
d w
ith
‘/l-in
. gl
ass
tuhc
~m
tnrr
vxl
into
a
aatu
rntc
d N
aHC
O,
solu
tmn.
H
eat
wlu
tion
on
hot-
plat
e to
hod
ta
r 20
mm
ute\
an
d th
en
plac
e in
coo
ling
tank
an
d al
low
to
co
ol
to 1
’oom
tcm
prnl
ture
. M
ake
sure
gi
n\\
outle
t tu
be
is
~mrm
rwd
III t
he
NaH
CO
,. R
emw
e st
oppe
r an
d ad
d rta
rch
wlu
tion.
Trrrm
r
ED
TA
Red
-blu
e
HC
I B
lue-
gree
n
HC
I
Col
orle
ss-b
lue
H@
0,)2
KI-K
ID,
Col
orle
ss-b
lue
M
ED
TA
= (W
I C
aCO
, x
1111
\wlp
le)l
(ml
ED
TA
X
50.0
5)
N
HC
I =
(M.t
Na,
CO
,)/
(IllI
x
0.05
299)
N
HC
I =
,wt
Nal
CO
,)/
(ml
x 0.
0529
9)
N
I2 =
(w
r A
\?03
1 (m
l X
11
.039
46)
N Hg
(NO
,),
= (w
t K
CI
x m
l r~
Inpl
c)i(m
l H
_s(N
O),)
~ X
74.
56)
N
KI-K
IO,
= (w
t S
ll)/(
rnl
x 0.
05Y
34S
)
Tabl
e IV
. St
ands
rdiz
atiu
n d
Ybnd
rrd
Solu
tions
(c
um.)
.s0f
rd0R
Ti
trant
C
olor
C
hang
e
Cul
cula
riom
(m
l, N.
M
-titm
t; wt
-sam
ple
in g
ram
s)
0.1
N KM
nO,
3.2
g KM
nO,
per
liter
Hz0
0.1
N KS
CN
9.7
g KS
CN
per
liter
W
0.1
AsNO
, 17
.0 I
: Ag
NO,
per
liter
HI0
0.1
N Na
OH
4.0
g Na
OH
per
liter
H,O
I .O
N Na
OH
4U.U
g N
aOH
per
liter
I&O
0.1
N Na
,S,O
., 25
.0 g
N+S
,O,+
H,
0 pe
r lite
r Ii,
0
0. I
N Th
(NO,
), 14
.0 g
l’h
(NO&
,4HL
0 pe
r lite
r H,
O
Heat
KM
nO,
solu
tion
to n
ear
bodi
ng
fu
30 m
inut
es
and
let
stand
ov
ernig
ht.
Filte
r th
roug
h a
aintcr
cd
glass
cru
cible.
Th
en,
to
stand
ardiz
e:
add
0.2
g IV
a,C,
O,,
200
ml
H,O,
30
ml
20%
H,
SO,,
beat
fo
185-
195’F
.
KMnO
,
0.3
I: AS
, 15
ml
50%
HN
O,,
100
ml
l&O,
an
d FA
S.
KSCN
0.2
t: Na
CI,
125
ml
H,O,
so
d K,
CrO,
.
0.5
g po
tass
ium
hydr
ogen
ph
thsla
te
(KHC
,H,O
,j,
125
ml
H,O,
an
d ph
enol
phth
alei
n.
4.0
g po
tawu
m
hydr
ogen
ph
tbal
ate
(KHC
,H,O
,),
I25
ml
H,O,
an
d ph
enol
phth
alei
n ind
icato
r.
Add
0.1
g N&
O.,
to N
&O,
solut
ton
and
let
stand
fo
r 24
hou
rs.
To s
tand
ardiw
ad
d 0.
12
g KI
O,,
2 g
KI,
25 m
l HZ
O,
and
8 m
l 10
% H
CI.
Titra
te
to l
ight
qe
llow
with
N+
S20,
an
d ad
d 2
ml
starch
so
lutio
n.
5.0
g Na
F dis
wlvc
d in
H,O
an
d Jd
uted
to
1,U
UU m
l in
a v
olum
etric
tla
sk.
Pipe
tte
l&m
l sa
mpl
e,
add
100
ml
H,O.
al
izarin
ind
icato
r, 2%
HN
U,.
dnrp
wisc
fro
m
pink
to y
ellu
w,
and
3 m
l flu
orid
e bu
ffer.
AiW
x
NaOH
NaOH
mNo
3),
Color
less-
pink
Color
less-
red
Yello
w-re
d
Color
less-
pink
Color
less-
pink
Blue
-colo
rless
Yello
w-pi
nk
NKM
nO,=
wt
Na
,C,O
,)/
(ml
X 0.
0670
)
N KS
CN
= (w
t Ag
)/ (m
l X
0.10
787)
N Ag
NO,
= (w
t N&
l)/
(ml
X 0.
0584
5)
N Na
OH
= W
~W
W,)/
(m
l x
0.20
422)
N
NaOH
=
(wt
KHC,
H,O,
)/ (m
l X
0.20
122)
N
N&O,
=
(wt
KIO,
)/(m
l x
0.03
567)
N =
(WI
NaF
per
liter)/
(ml
X 4.
1998
)
Table V. Indicators for Analyses
I .O g sodium alirarm sulfonate. I .nnO ml HzO. 0.4 g bromocresol green, 1,000 ml H,O, 0 5 ml I .O N NaOH. 0.4 8 bromocresnl purple, I.000 ml HzO. I .O ml I .O N NaOH. 2.0 s Eriochrome Black T, I98 ~0 NaCI. 5.0 g Eriochrome Black T, 150 ml methanol. 100 ml trlethanolamlne. SO p ferrous ammoGum wlfntc, 950 ml HLO. In ml cwt. HNO,. 20 g KJrO,. 9X0 ml H,O. 1 .O s methyl orange (sodium \altL I.000 ml H,O. 2.0 g murexide. 198 g NaCI. I .O g peroxyacetal nitrate. I.000 ml methanol. I.0 g phenolphthalein. 500 ml cthsnol. 500 ml HzO. IO.0 g ?tarch. 1.000 ml hot H,O, 0.5 ml formaldehyde. IO0 ml sulfa oran,q. IO g NaCN. 845 ml H>O.
40 g nmmon~um oxalate, 960 ml HzO. IO s dimethylglyoxime. I.000 ml ethanol. 01solve 40 g monochloroacetic aad in 400 ml Hz0 and divide the
solutmn m two equal parts. Add phenolphthalein to one pal-t alld titrate with I .O N NaOH f~rwn coIorlew to pink Mix both parts and add HZ0 to 1,000 ml.
100 g KF dirsolved in 1,000 ml HzO. Neutralize to pH 7.0 with I .O N NaOH.
IO0 g NaCN, 900 ml H,O. I35 g Na,SO,, 950 ml &O 3SO ml cont. NH,OH, S4 g NH,CI, 625 ml H20. I00 ml cont. HCI. 250 ml cont. HC,H,O,. 200 ml ethanol.
4.50 ml H,O. 200 g Kochelle wits, X00 ml H?O. 2.0 g SbCI,. 100 ml 50% HCI. IO s AgNO,, 95 ml H,O. I00 g sodium sulfite, 950 ml H,O. Ad,ju\t to pH 9.0 with I.0 N
NaOH or I.0 N HCI. Solution ha\ a I-week shelf hfe. IS0 g tartaric acid, 950 ml H20.
I .oso I.365 I .220 1.490 I.181 I .256 I.420 I.690 I.835
Porrr~dr/Gall,m
X.76 I I .3X in.17 Il.43
9.87 IO.48 1 I XJ 13.09 IS.30
536
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
Erus
c C
uCN
(M
etho
d I)
2 m
l
CuC
N
(Met
hod
11)
2 m
l
Zn(C
N),
5 m
l
NaC
N
or
5 m
l KC
N
NaO
H or
5
ml
KOH
Na,C
O,
or
IO m
l
KG’,
IS m
l co
nt.
HNO
,. he
at t
o bl
ue c
olor
, IO
0 m
l H,
O,”
cont
. NH
,OH
to d
eep
blue
, he
at t
o 14
0°F.
an
d ad
d PA
N.
0.1
M
EDTA
100
ml
HzO
. 15
ml
cow.
HN
O,,
heat
to
0.1
N N&
O,
blue
col
or
and
disa
ppea
ranc
e of
bro
wn
fum
es,
NH,O
H to
dee
p bl
ue.
acet
ic ac
id
to l
ight
bl
ue,
5 g
KI.
Titra
te
with
N&
O,
to p
ale
yello
w.
add
5 m
l st
arch
so
lutio
n,
cont
inue
tit
ratin
g to
col
orle
ss.
IO0
ml
H,O
, 10
ml
pH
IO b
uffe
r, EB
T po
wder
, an
d I5
ml
10%
for
mal
dehy
de.
0. I
M E
DTA
100
ml
H,O
an
d 10
ml
IO%
KI
. 0.
1 N
AgNO
,
25 m
l Hz
0 an
d 5
ml
culfo
-ora
nge.
1.
0 N
HCI
100
ml
hot
H,O
, 35
ml
10%
Ba(
NO&.
al
low
to
set
tle.
filte
r. wa
sh
filte
r tw
ce
with
ho
t H,
O,
trans
fer
filte
r pa
per
and
prec
ipita
te
to a
bea
ker.
add
lo0
ml
H,O
, an
d m
ethy
l or
ange
.
I .O
N H
Cl
Purp
le-g
reen
C
uCN
(&
gal)
= 2.
985
X M
X
[2
X C
uCN
m
l -
0.8
X Zn
(CN)
, m
l]
Blue
-col
orle
ss
CuC
N
(or/g
al)
= m
l X
5.97
1 X
N
Red
-blu
e Zn
(CN)
, (o
~iga
l) =
ml
X 3.
131
X M
Cle
ar-tu
rbid
N
aCN
(o
z/ga
l) =
ml
X 2.
614
X N
KCN
to
&gal
) =
ml
X 3.
473
X N
Ora
nge-
yello
w Na
OH
(o&a
l) =
ml
X 1.
067
X N
KOH
(or/g
al)
= m
l X
1.49
6 X
N
Ora
nge-
pmk
Na,C
O,
(or/g
al)
= m
l X
0.70
7 X
N
K&O
, (o
71gz
.l) =
m
l X
0.92
1 X
N
Tubl
e VW
. Te
st
Met
l~u&
fu
r El
wtru
plat
ing
Sulu
tiuns
~w
~r.)
Burt1
KNaC
,H,0
,.4H
20
Btw
n~e
Cu
(Met
hod
I)
Heag
enrs
Su
rnpl
e Si
re
(To
be d
ied
in u
&r
liste
d)
Titru
nt
Col
or
Cha
nge
Cal
cula
tions
(m
l. iV
. M
-tirr
unt)
5 m
l 25
ml
20%
H,
SO,.
filte
r, wa
sh
tIa%
k an
d 0.
1 N
KMnO
, Co
lorle
ss-p
ink
KNaC
,H,0
,,~4H
aO
(ozl
gal)
= fil
ter
pape
r tw
ice
each
with
H,
O,
and
ml
X 1.
250
X N
boil
the
colle
cted
fit
trate
5
min
utes
,
2 m
l 15
ml
cont
. HN
Os,
he
at t
o bl
ue c
olor
, 0.
I M
ED
TA
Purp
le-g
reen
C
u (o
z/ga
l) =
ml
X 4.
236
X M
lo
0 m
l H,
O,
cont
. NH
,OH
to d
eep
blue
. he
at t
o Ill
O’F
an
d dd
PA
N.
Cu
(Met
hod
II)
Sn
2 m
l 10
0 m
l H,
O.
I5 m
l co
rm.
HNO
,, he
at t
o bl
ue c
olor
an
d di
sapp
eara
nce
of b
rown
fu
mes
, NH
,OH
to d
eep
blue
, ac
etic
acid
to
lig
ht
blue
, 5
g KI
. Ti
trate
w
ith
Na,S
,O,
to p
ale
yello
w,
add
5 m
l st
arch
so
lutio
n,
cont
inue
tit
ratin
g to
col
orle
ss.
0. I
N N
a,S?
O,
Blue
-col
orle
ss
Cu
(ozl
gal)
= m
l X
4.23
6 X
N
5 m
l 10
0 m
l H
20.
50 m
l co
nt.
HCI,
3.0
g iro
n 0.
1 N
KI-K
IO,
Cle
ar-b
lue
Sn (
or&I
) =
ml
X I.5
113
X N
powd
er
in 5
00.m
l tla
sk.
Stop
per
flask
w
ith
stop
per
litte
d w
ith
a gl
ass
tube
Im
mer
sed
in a
bea
ker
fille
d w
ith
satu
rate
d bi
carb
onat
e so
lutio
n.
Hea
t ge
ntly
til
l iro
n di
ssol
ves.
C
ool
to r
oom
te
mpe
ratu
re,
mak
ing
sure
ou
tlet
tube
is
imm
erse
d in
bic
arbo
nate
so
lutio
n.
Add
10 m
l st
amh
solu
tion
and
bica
rbon
ate
durin
g tit
ratio
n.
NaC
N
or
KCN
5
ml
IO0
ml
Ha0
an
d IO
ml
IOKI
. 0.
1 N
AgNO
, C
lear
-turb
id
NaC
N
(&ga
l) =
ml
X 2.
614
X N
KCN
(o
r/gal
) =
ml
x 3.
473
x N
NaO
H or
KO
H 5
ml
25 m
l Hz
0 an
d S
ml
rullo
-ora
nge.
I .
o N
tic1
Ora
nge-
yello
w Na
OH
(otig
al)
= m
l x
I.067
x
N KO
H (o
z./g
al)
= m
l X
I.496
X
N
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
(con
t.)
Bat
h S
ump/
e S
ix!
NaJO
, or
IO
ml
K&O
,
KNaC
,H,0
,.4H
I0
Cud
miu
m
Cym
ide
Cd
Tota
l an
d Fr
ee N
aCN
NaO
H
NnJO
,
5 m
l
2 m
l
5 m
l
s m
l
10 m
l
100
ml
hot
HzO
, 35
ml
10%
Ba(
NO&,
al
low
to
set
tle,
filte
r, wa
sh
filte
r tw
ice
with
ho
t H,
O,
trans
fer
filte
r pa
per
and
prec
ipita
te
to a
bea
ker,
add
100
ml
H20
an
d m
ethy
l or
ange
.
25 m
l 20
%
H,SO
,, fil
ter,
wash
fla
sk
and
filte
r pa
per
&ice
ea
ch w
ith
H,O
. an
d bo
il th
e co
llect
ed
filtra
te
5 m
inut
es.
100
ml
H,O
, 10
ml
pH
IO b
uffe
r, EB
T po
wder
, an
d IS
ml
10%
for
mal
dehy
de.
100
ml
HzO
, 15
ml
cow.
NH
,OH,
an
d IO
ml
10%
KI.
25
ml
HZ0
and
5 m
l su
lfa-o
rang
e.
IO0
ml
hot
HZO
, 3.
5 m
l 10
% B
a(NO
&,
allo
w
to s
ettle
, fil
ter,
wash
filt
er
twce
w
ith
hot
HzO
, tra
nsfe
r fil
ter
pape
r an
d pr
ecip
itate
to
a b
eake
r, ad
d 10
0 m
l H,
O
and
met
hyl
oran
ge.
100
ml
H20
, IO
ml
pH
IO h
uffc
r, EB
T po
wder
, an
d 15
ml
10%
for
mal
dehy
de.
1.0
N HC
I
0.1
N KM
nO,
0.1
M E
DTA
0.1
N Ag
NO,
I .O
N H
CI
I .O N
HCI
0.1
M E
DTA
Ora
nge-
pmk
NaJO
, (a
dgal
) =
ml
x 0.
707
x N
KLCO
, (o
&d)
= m
l x
0.92
1 X
N
Colo
rless
-pin
k KN
aC,H
,0,.4
H20
(o
r/gal
) =
ml
X 1.
250
X N
Red
-blu
e C
d (o
r/gal
) =
ml
x 7.
493
X M
Cle
ar-tu
rbid
To
tal
NaC
N
(ozl
gal)
= m
l X
2.61
3 X
N Fr
ee
NaC
N
(or/g
al)
= To
tal
NaC
N
- 1.
744
X C
d O
rang
e-ye
llow
NaO
H (o
zlga
l) =
ml
X I.0
67
X N
Ora
nge-
pink
Na
JO,
(w/g
al)
= m
l X
0.70
7 X
N
Red
-blu
e C
d (w
/gal
) =
ml
x 7.
493
X M
3
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
(um
r.)
Co/~
/w
Cw
mid
e C
uCN
(M
etho
d I)
CuC
N
(Met
hod
II)
25 m
l 10
0 m
l H
,O.
100
ml
rcdu
cmg
solu
tion.
ho
i1 3
0 m
inut
es,
rem
ove
from
he
at,
add
SO
ml
10%
B
a(N
O?)
,, 10
0 m
l ho
t H
,O.
Allo
w
aolu
tmn
to
wnd
fo
r 31
1 ho
urs,
he
at
solu
tion
to
bolh
ng.
Filte
r in
tar
ed
Goo
ch
cruc
ible
, w
ash
prea
pita
te
wth
ho
t H
:O,
dry
in o
ven
at 1
10°C
. co
ol
,n
dew
catn
r an
d w
afh.
SO
, (d
pall
= (w
eigh
t tn
:rn
ms
of
prec
ipita
te)
x 2.
195
5 m
l 10
0 m
l H
,O,
I.0
N
NaO
H
to p
H
7.5.
0.
I N
Th(
NO
,),
Yel
low
-pin
k F
(o-r
&d)
=
ml
X
0.50
7 X
N
usin
g a
pH
met
er
prev
ious
ly
stan
dard
tzed
to
pH
7.
0.
Add
10
%’
AgN
O,
solu
tion
until
th
e dl
sapp
eartw
ce
of
the
yrlln
w
colo
r af
ter
scttl
inf
of
the
prec
ipita
te,
flltc
r, w
ash
prcc
iput
e,
swe
filtr
ate.
A
dd
Alir
arm
In
dica
tor.
2%
HN
O,
till
colo
r of
w
lutio
n ch
ange
s fro
m
pink
to
yel
low
. A
dd
3 m
l tlu
orld
c hu
ffer.
2 m
l IS
ml
cont
. H
NO
,. he
at t
o bl
ue
C&
II-.
100
~ml H
>O,
cont
. N
H,O
H
to d
eep
hluc
. hu
t to
14
0°F.
an
d ad
d P
AN
.
0.1
M
ED
TA
PW
ple-
prW
l C
uCN
(o
&d)
=
ml
X 5
.971
X
M
2 m
l 10
0 m
l H
ZO.
IS m
l co
w.
HN
O,.
heat
to
bl
ue c
olor
an
d di
sapp
eara
nce
of
brow
n fu
mes
, N
H,O
H
to d
eep
blue
. ac
etic
ac
td
to l
ight
bl
ue,
5 g
KI.
Titra
te
wth
N
a,S
,O,
to p
ale
yello
w.
add
5 m
l st
arch
w
lutio
n,
cont
inue
tit
ratin
g to
col
orle
u.
0.1
N N
a,S
,O,
Blu
e-co
lorle
ss
CuC
N
(w/g
al)
= m
l X
5.9
71
X
N
E N
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
(wn~
.)
NaC
N
or
KCN
NaO
H 01
KO
H
KNnC
,H,0
;4H
20
Cu
(Met
hod
II)
5 m
l
5 m
l
IO m
l
5 m
l
2 m
l
2 m
l
IO m
l
2 m
l
I00
ml
H,O
an
d IO
ml
IO%
KI
.
25 m
l Hz
0 an
d 5
ml
aulfo
-ora
nge.
I00
ml
hot
H,O
, 35
ml
10%
Ba
(NO
,)>.
~110
~ tu
set
tle.
filte
r, wa
sh
filte
r tw
ice
with
ho
t HZ
O.
trans
fer
filte
r pa
per
and
prec
ipita
te
to a
bea
ker,
add
100
ml
H,O
, an
d m
ethy
l or
ange
.
2S m
l 20
%
H2S
0,,
filte
r, wa
sh
flask
an
d fil
ter
pape
r tw
ice
each
with
Hz
O.
and
bow
l the
col
lect
ed
filtra
te
5 m
inut
es.
100
ml
H,O
, co
w.
NH,O
H to
dee
p bl
ue,
heat
to
140-
F.
and
add
PAN
IO0
ml
HLO
, NH
,OH
to d
eep
blue
, ac
ctw
acid
to
light
blu
e,
5 g
KI.
Titra
te
with
N&
O,
to p
ale
yello
w,
add
5 m
l st
arch
w
lutio
n,
cont
inue
tit
ratin
g to
W
lWl%
S.
IO0
ml
Hz0
and
met
hyl
oran
ge.
100
ml
H,O
co
nt.
NH,O
H to
dee
p bl
ue.
heat
to
140°
F an
d ad
d PA
N.
0.1
N Ag
NO,
I .O
N H
CI
I .O
N H
CI
0.1
N KM
nO,
0.1
M E
DTA
0. I
N N
a2S2
0,
I .O
N N
aOH
0.1
M E
DTA
Clea
r-tttr
btd
Ora
nge-
yello
w
Ora
nge-
pink
Colo
rless
-pin
k
Purp
le-g
reen
Blue
-col
orla
s
Red-
pree
n
NCN
(w/g
al)
= m
l X
2.61
4 X
N KC
N
(w/g
al)
= m
l x
3.47
3 X
N
NaO
H (o
ziga
ll =
ml
x I.0
67
x N
KOH
(ozi
fal)
= m
l X
1.49
6 X
N
Na,C
O,
(~&V
I) =
ml
X 0.
707
X N
KJO
,. et
c K,
CO,
(o//g
al)
= m
l x
ll.Y2
1 X
N
KNaC
,H,O
,.4H,
O
(w/g
al)
= m
l x
I.250
X
N
Cu
(o&l
) =
ml
X 4.
236
X M
CU
BF,),
i&
gal)
= C
u X
3.73
Cu
(ozl
gal)
= m
l x
4 2%
X
N
lOO
r/,
HBF
, (o
z/.&
) =
ml
X I.1
71
X N
Cu
(or/g
al)
= m
l X
4.2X
1 X
M
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
(con
r.)
Bat
h S
ampl
e S
ize
Rea
gent
s (T
o he
add
ed
in o
rder
lis
ted)
Ti
VfW
U
Col
or
Cha
nge
Cal
cula
tions
(m
l. N
. M
-titra
nt)
Cu
(Met
hod
II)
2 m
l
Tota
l P,
O,
5 m
l
100
ml
H,O
, NH
,OH
to d
eep
blue
, ac
e-
0.1
N Na
,S>O
, Bl
ue-c
olor
less
tic
aci
d to
lig
ht b
lue,
5
g KI
. Ti
trate
w
ith
Na&O
, to
pal
e ye
llow
, ad
d 5
ml
star
ch
solu
tion,
co
ntin
ue
titra
ting
to c
olor
less
. 10
0 m
l H,
O,
1.0
N H
Cl
drop
wise
to
pH
I .
O N
NaO
H 3.
8 (u
se p
H
met
er
stan
dard
ized
at
pH
4.
0),
back
-titra
te
with
1.
0 N
NaO
H if
pH
3.8
is ov
ersh
ot,
stir
5 m
inut
es
and
mak
e su
re p
H
is 3.
6-3.
8,
add
50 m
l 20
%
ZnSO
, (a
djus
ted
to p
H
3.8)
and
stir
IO
m
inut
es.
Titra
te
slow
ly
with
st
inin
g us
ing
1 .O
N N
aOH
to p
H
3.8
(not
e th
ese
ml
NaO
H us
ed f
or
calc
ulat
ion)
.
10 m
l 20
0 m
l Hz
O,
boili
ng
chip
s,
50 m
l 20
%
NaO
H III
Kje
ldab
l fla
sk.
Atta
ch
flask
to
th
e di
still
atio
n ap
para
tus
with
th
e co
llect
ion
tube
fro
m
the
cond
ense
r im
mer
sed
m a
bea
ker
cont
aini
ng
100
ml
satu
rate
d H,
BO?
solu
tion.
Bo
il fla
sk
and
diqt
dl
over
10
0 m
l. Re
mov
e be
aker
an
d ad
d m
ethy
l or
ange
.
0.1
N HC
I Ye
llow
-red
Cop
per
sulfa
te
Cu
(Met
hod
I) 2
ml
100
ml
HzO
, co
nt.
NH,O
H to
dee
p bl
ue,
heat
to
140°
F.
and
add
PAN
. 0.
1 M
ED
TA
Purp
le-g
reen
Cu
(Met
hod
II)
2 m
l 10
0 m
l H,
O.
NH,O
H to
dee
p bl
ue,
acet
ic ac
id
to l
ight
bl
ue,
5 g
KJ.
Titra
te
with
Na
,S,O
, to
pal
e ye
llow
, ad
d 5
ml
0.1
N N&
O,
BIIE
COlO
TkSS
star
ch
solu
tion,
co
ntin
ue
titra
ting
to
colo
rless
.
Cu
(oz/
gal)
= m
l X
4.23
6 X
N
Tota
l P,
O,
(oz/
gal)
= m
l X
2.32
X
N +
Cu
X 1.
37
Rat
io
= [T
otal
P,
O,
(oz/
gal)l
lCu
Cod
gal)
29%
NH
, (o
z/ga
l) =
ml
x 0.
80
x N
Cu
(&ga
l) =
ml
X 4.
236
X M
C
uS0,
.5H
z0
(oz/
gal)
= C
u X
3.93
Cu
(w/g
al)
= m
l X
4.23
6 X
N
W
r
4
-2
545
t
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
(mu.
)
-
Ni
NaS
CN
Nick
el
Fluo
bnm
fr N
i HP%
Nick
el
Strik
e N
i
HC
I
Nick
el
Sulfa
mut
e N
i
NiB
rz
NiC
12.6
H,0
WC
’,
2 m
l
10 m
l
2 m
l
IO m
l
2 m
l
10 m
l
2 m
l
5 m
l
20 m
l
IO m
l
100
ml
H,O
, IO
ml
cow
N
H,O
H,
and
mur
exid
e po
wde
r.
100
ml
H,O
, 15
ml
20%
H
$O,,
and
FAS
in
dica
tor.
100
ml
HzO
, IO
ml
cow
. N
H,O
H,
and
mur
exid
e po
wde
r.
25 m
l H
20,
5.0
g m
anni
tol,
and
brom
ocre
sol
purp
le.
100
ml
H,O
, 20
ml
cont
. N
H,O
H,
and
mur
exid
e po
wde
r.
IO
ml
HZ0
an
d m
ethy
l or
ange
.
100
ml
HzO
, 20
m
l co
nt.
NH
,OH
, an
d m
urex
ide
pow
der.
100
ml
H,O
an
d K
,CrO
,.
100
ml
HZ0
an
d K
ZCrO
,.
25 m
l H
ZO.
5.0
g m
anni
tol,
and
hrom
ocre
sol
purp
le.
Titra
nr
Col
or
Chu
n@?
Cal
culu
tions
(m
/, N,
M-ri
tmnr
)
0.1
M
ED
TA
0.1
N
AgN
O,
0.1
M
ED
TA
I .O
N N
aOH
0.1
M
ED
TA
1 .O
N
NaO
H
0.1
M
ED
TA
0.1
N
AgN
O,
0. I
N
AgN
O,
I .O
N
NaO
H
Ora
nge-
purp
le
Red
-col
orle
ss
Ni
(w/g
al)
= (m
l E
DTA
fo
r N
i -
ml
ED
TA
for
Zn)
X
3.91
4 X
M
NaS
CN
(o
z./g
al)
= m
l X
I.0
81
X
N
Ora
nge-
purp
le
Gre
en-p
urpl
e
Ora
nge-
purp
le
Red
-yel
low
/gre
en
Ora
nge-
purp
le
Yel
low
/gre
en-r
ed
Yel
low
/gre
twed
Gre
en-p
urpl
e
Ni
(or/g
al)
= m
l X
3.
914
X M
H,BO
, (“
z/ga
l) =
ml
x 0.
824
x N
Ni
(o&
gal)
= m
l X
3.
914
X M
36%
H
CI
(tl
oz./g
al)
= m
l X
I.1
IS
x
N
NI
(oz/
pal)
= m
l x
3.91
4 x
M
NiB
r,
(oz1
gal)
= m
l X
2.
914
X
N
NiC
l,.6H
z0
(ozl
gal)
= m
l x
0.79
2 x
N
H,B
O,
(oz.
/gal
) =
ml
X
0.82
4 X
N
c
0
548
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
(con
t.)
Rut
h S
amD
Ie S
ix7
Rea
gent
s (T
o be
add
ed
in o
rder
lis
ted)
Ti
rrun
t C
olor
C
hann
e C
alcu
lutim
r (m
l. N
, M
-titru
nt)
Pal
ladi
um
Pd
Pla
tinum
Pl
Rho
dium
R
h
IO m
l IO
ml
cont
. HN
O,,
heat
unt
d sy
rupy
, IO
m
l co
nt.
HNO
,, he
at t
o on
set
of b
oilin
g.
Add
250
ml
H,O
, co
ol,
slow
ly
add
40
ml
dim
ethy
lgly
oxim
e so
lutio
n,
allo
w
solu
tion
to s
tand
at
leas
t 2
hour
s,
filte
r th
roug
h N
o. 3
por
osity
ta
red
cruc
ible
, wa
sh
prec
ipita
te
with
H
20.
Dry
in o
ven
at 1
IO’C
, co
ol
m d
esicc
ator
, an
d w
eigh
.
IO m
l 10
ml
cont
. HC
I, he
at u
ntil
syru
py,
100
ml
H,O
, 5
g so
dium
ac
etat
e,
1 m
l co
nt.
form
ic
acid
, he
at a
t l4
0’F
for
5 ho
urs,
fil
ter,
wash
pr
ecip
itate
w
ith
hot
H,O
. Pl
ace
filte
r pa
per
and
Pt p
reci
pita
te
in
tare
d po
rcel
ain
cruc
ible
, dr
y sl
owly
w
ith
Buns
en
burn
er,
char
fil
ter
pape
r, dr
y Pt
pr
ecip
itate
at
hig
h te
mpe
ratu
re
for
30
mm
utes
. C
ool
in d
esicc
ator
an
d w
eigh
.
25 m
l 2
g M
g tu
rnin
gs,
cont
. HC
I dr
opwi
se.
Whe
n al
l M
g di
ssol
ves,
ad
d 0.
5 g
Mg
tum
mgs
an
d HC
I dr
opwi
se
to e
nsur
e co
mpl
ete
prec
ipita
tion
of R
h.
Filte
r so
lutio
n in
tar
ed G
ooch
cr
ucib
le
cont
aini
ng
fiber
glas
s fil
ter
pape
r, wa
sh
prec
ipita
te
with
ho
t Hz
O,
dry
in o
ven
at
I IO
’C,
cool
in
des
iccat
or
and
wei
gh.
Pd (
g/L)
=
(wei
ght
in g
ram
s of
pr
ecip
itate
) X
3 I .6
7
Pt (
g/L)
=
(wet
ght
in g
ram
s of
pr
ecip
itate
) X
100.
0
Rh
(g/L
) =
(wei
ght
in g
ram
s of
pr
ecip
itate
) X
40.0
WO,
or IO
ml
100
ml
H,O
an
d m
ethy
l or
ange
. I .
O N
NaO
H R
ed-y
ello
w/g
reen
10
0% H
,SO
, (g
/L)
= m
l X
4.90
4 X
N
E!
HP%
10
0% H
,PO
, (g
/L)
= m
l X
9.80
0 X
N
W
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
(con
t.)
Buth
SIld
+
Keu,
Lynr
s - Sm
ple
six
(To
be a
dded
bt
ord
er-
liste
d)
Titru
nt
Col
or
Cllu
n,~r
~‘
dulu
tions
(m
l, N
, M
-trtm
t)
2 11
11
In 5
00-m
l fla
sk
add
sam
ple,
III
0 m
l 0.
1 N
KI-K
IO,
Cok
IrleS
S-bl
Ue
SnJ+
(o
/gal
) =
ml
X 3.
Y.56
X N
-
cow.
H
Cl,
2 dr
ops
ShC
I, so
lotlo
n.
Add
S”L+
IX0
ml
H>O
. Si
n.
fold
ed
‘V-s
hape
d ni
ckel
st
rip
and
5.0
g re
duce
d no
n po
wder
. St
oppe
r fla
sk
with
ru
hhet
<t
oppe
r fit
ted
wth
%
-in.
&is\
tu
be
lmm
erae
d in
to a
sat
urat
ed
NaHC
O,
wlu
tion.
H
eat
solw
on
on h
ot p
late
to
hoi1
for
20 m
inut
es
and
then
pla
ce i
x co
olin
g ta
nk
and
allo
w
to c
ool
to r
oom
te
mpe
ratu
re.
Mak
e W
C gl
ass
outle
t tu
hc
IS u
mne
rsed
in
the
NRU
CO,.
Rem
ove
stop
per
and
add
star
ch
aolu
tirn.
HBF
, IO
ml
Free
H,B
O,
IO m
l
100
ml
HLO
an
d m
ethy
l or
ange
. I.0
N
NaO
H C
lear
-turb
id
100%
HBF
, (o
r/gal
) =
ml
X
I.171
X
N
100
ml
H20
, IO
ml
Na2
S0,
solu
tion.
Ti
trate
to
pH
7.0
, us
ing
a pH
m
eter
pr
evio
usly
stan
dard
ized
to
pH
7.0
. Ad
d S
g m
anm
tol,
titra
te
from
pH
7.
0 to
pH
X.
0 (m
l Na
OH
requ
ired
for
thin
ste
p w
e us
ed
for
the
calc
ulat
ion)
.
I .tl
N Na
OH
H,BO
, (o
r/gal
) =
ml
X 0.
824
X N
Tin
Sran
nate
K
ZSn0
,.3H
Z0
Naz
S”0
,.3H
z0
5 m
l 10
0 m
l H
,O.
50
ml
cont
. H
CI.
3.0
g iro
ll 0.
I N
K
I-KIO
, C
OlO
ibS-
blue
K
,Sn0
,.3H
I0
(cr//
g;d)
=
“~1
X
3.98
6 X
po
wde
r in
S
W-m
l tla
sk.
Sro
pper
lla
sk
N
with
st
oppe
r fit
ted
with
a
glas
s tu
be
Na,
Sn0
,.3H
10
Wga
ll =
imm
crsc
d in
a b
eake
r fil
led
with
m
l x
3.5%
x
N
KO
H
NaO
H
Tin
Sulfu
te
snso
,
S”4’
satu
rate
d bi
carb
onat
e so
lutio
n.
Hea
t ge
ntly
til
l iro
n di
ssol
ves.
C
ool
IO r
o+)ln
te
mpc
rattu
rc,
mak
ing
sure
ou
tlet
tuhr
is
im
mer
sed
in b
icar
bona
te
solu
tion.
A
dd
10 m
l st
arch
so
lutio
n an
d bi
carb
onat
e du
ring
titra
tion.
5 m
l 25
ml
H,O
an
d S
ml
sulfo
-ora
nge
1.0
N
HC
I O
rang
e-ye
llow
K
OH
(o
x&l)
= “1
1 X
I.1
96
X
N
NuO
H
(o/&
al)
=- “
11 X
1.
067
X
N
5 m
l 10
0 m
l H
20,
25 m
l 50
%
HC
I, IO
ml
star
ch
solu
tion,
ad
d bi
carb
onat
e du
ring
titra
tion.
0.1
N
KI-K
IO.,
Col
orle
ss-b
lue
SnS
O,
(oz.
/gel
) r
ml
X
‘.X63
X
N
S
””
(oz.
/gal
) =
SnS
O,
x 0.
5.53
2 m
l In
SW
-ml
fla.k
ad
d sa
mpl
e.
100
ml
0.1
N
KI-K
IO,
Col
orle
ss-b
lue
Sn4
+ (o
Ilgal
) =
cont
. H
CI,
2 dr
ops
SbC
I, so
lutio
n.
Add
m
l x
3.95
6 X
N
.-
Sn”
18
0 m
l l-1
,0.
5-i”.
fo
lded
“U
’-sha
ped
nick
el
strip
an
d 5.
0 g
redu
ced
imn
pow
der.
Sto
pper
fla
sk
with
ru
bber
st
oppe
r fit
ted
with
%
-in.
glas
s tu
be
imm
erse
d in
to
a sa
tura
ted
NaH
CO
, so
lutio
n.
Hea
t so
lutio
n on
ho
t-pl
ate
to
boil
for
20
min
utes
an
d th
en
plac
e in
co
olin
g ta
nk
and
allo
w
IO c
ool
to
room
te
mpe
ratu
re.
Mak
e su
re
glas
s ou
tlet
tube
is
im
mer
sed
in t
he
NaH
CO
,. K
rmov
e st
oppe
r an
d ad
d st
arch
so
lutio
n.
Tabl
e VI
II.
Test
M
etho
ds
for
Elec
tropl
atin
g So
lutio
ns
(wm
.J
HZS
O,
100
ml
H,O
, 25
ml
amm
oniu
m
oxal
ate
solu
tion,
an
d m
ethy
l or
ange
. I .
O N
N
aOH
R
ed-
100%
H
:SO
, (o
r/gal
) =
ml
X
0.65
4 or
anpc
/yel
low
%
v
H,S
O,
= m
l X
0.
279
X
N
100
ml
H,O
, 25
m
l S
O6
HC
I, IO
ml
star
ch
0.1
N
KI-K
IO,
Col
orle
\\-bl
ue
St?
(w
&al
) =
ml
X
3.95
6 x
N
sufu
t~on
, ad
d bu
rbon
ate
durin
g te
non
St?
+ 2
ml
In
St&
ml
flask
ad
d sa
mpl
e,
I00
ml
cow
. H
CI,
2 dr
ops
SbC
I, so
Iut\w
. A
dd
180
ml
H,O
, 5-
in.
fold
ed
“Wsh
aped
ni
ckel
st
rip
and
5.0
g re
duce
d ~r
nn
pow
der.
Sto
pper
fla
sk
with
ru
bber
st
oppe
r flt
ted
wth
%
-in.
glas
s tu
be
Imm
ened
in
to
;t ut
urat
ed
NaH
CO
, w
lutio
n.
Hea
t so
lutio
n on
hot
-pla
te
to
boil
I’or
20
min
utes
an
d th
en
plac
e m
co
olin
g ta
nk
and
allo
w
to c
ool
to w
orn
tem
pera
ture
. M
ake
cure
gl
a\\
outle
t tu
be
is i
mm
erse
d in
the
NaH
CO
,. R
emw
e st
oppe
r an
d ad
d \ta
rch
\oI~
t~m
~.
0.1
N
KI-K
IO,
Col
orle
ss-b
lue
Sn”
(o
&al
) =
ml
x 7.
956
X N
-
Sn“
Ph
2 m
l 5
ml
cow
. H
NO
,, he
at t
ill
sym
py.
cool
an
d ad
d:
25 m
l R
oche
lle
solu
tmn,
IS
m
l co
nt.
NH
,OH
, 15
ml
10%
N
aCN
an
d E
BT
solu
tion.
0. I
M
ElIT
.4
Red
-blu
e P
b to
rigal
) =
1111
X
13.X
13 X
M
HBF
, IO
ml
100
ml
H,O
. I .
O N
N
aOH
C
lcsr
-tul-h
id
1004
H
BF,
(o
ziga
l) =
ml
X
I.171
X
N
E
554
555
The Technology of Anodizing Aluminum,
Third Edition by A. II? Brace
410 pages $210.00
NE WEDITION This valuable book has been completely re- edited and considers signifi- cant new developments in anodizing technology. The expanded volume will satisfy the anodizer who requires more detailed technology. After an introduction, the reader is presented with practi- cal application of the new technology, and the nature of the industry with capital investment appraisal, budget- ing, and cost control. An excellent summary of anodiz- ing technologies in clear lan- guage encompassing the advice of exierienced technicians.
Send Orders to: METAL FINISHING
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Pmxdure: I. Cool the solution to room temperature after tating. 2. Dctemine the demity 01 the soluuon with a F&m& hydrometer. 3. Read the or/gal OS chrrmmw aud (CrOj) corre~pondm~ to thl\ dcmily
Chromium Plating by R. Weiner and A. W&r&y 239 pages $115.00
A thorough and well-written book on both decorative and engineering (hard) chromium plat- ing, it will be of interest to anyone engaged in production chromium plating and also to stu- dents, researchers, and design engineers. Anyone contemplating the installation of chromium plating facilities will find it of special value.
Send Orders to: METAL FINISHING., 660 White Plains Rd., Tarrytown, NY 10591-5153
For faster service, call (914) 333-2578 or FAX your order to (914) 333-2570
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Printed Circuits Handbook, Fourth Edition by CF. Coombs, Jr. 914 pages $90.00
This how-to book is a must for the practioner’s technical shelves and is required reading for anyone involved with the everyday PI-ohlrms arising in p rimed circuit manufacture. All aspects of the fabrication process are considered.
Send Orders to: METAL FINISHING, 660 White Plains Rd., Tarrytown, NY 10591-5153 For faster srrwce, call (914) 333-2578 or FAX pour order to (914) 333-2570
