This standard is issued under the fixed designation D ; the number 1 These test methods are under the jurisdiction of ASTM Committee D19 on. Buy ASTM D Standard Test Methods for Acidity or Alkalinity of Water from SAI Global. ASTM: D Acidity or Alkalinity of water by electrometric titration Annual Book of ASTM Standards, Section 11, Water and Environmental Technology.
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A number in parentheses indicates the year of last reapproval.
ASTM D 水的酸性和碱性的测试方法_百度文库
A superscript epsilon e indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. Three test methods are given as follows: Of the three procedures, Test Method A is the most precise and accurate. It is used to develop an electrometric titration curve sometimes referred to as a pH curvewhich de?
In addition, the acidity or alkalinity can be determined with respect to any pH of particular interest. The other two methods are used to determine acidity or alkalinity relative to a predesignated end point based on the asttm in color of an internal indicator or the equivalent end point measured by a pH meter.
They are suitable for routine control purposes. When titrating to a selected end point dictated by practical considerations, 1 only a part of the actual neutralizing capacity ashm the water may be measured, or 2 this capacity may actually be exceeded in arriving at aastm acidity or alkalinity conditions.
It is the responsibility of the analyst to determine the acceptability of these test methods for each matrix. Refer to Appendix X4 for historical information.
It is the responsibility of the user of this standard aastm establish appropriate safety and health practices and determine the aztm of regulatory limitations prior to use. Current edition approved Jan. Originally published as D — Last previous edition D — Only the particular adaptation of the electrometric titration appearing as the Referee Method is believed to be largely the work of Committee D A discussion of terms is presented in Appendix X1.
Purity of Reagents 5.
Unless otherwise indicated, it is intended that all reagents shall conform to the speci? In addition, reagent water for this test shall be free of carbon dioxide CO2 and shall have a pH between 6.
Other reagent water types may be used provided it is?
Type III water was speci? A procedure for the preparation of carbon dioxide-free water is given in Practice E It is mandatory that analyses by Test Method A be carried out the same day the samples are taken; essentially immediate analysis is desirable for those waste waters containing hydrolyzable salts that contain cations in several oxidation states.
It is used for the development of a titration curve that will de? The acidity or alkalinity of the water or that relative to a particular pH is determined from the curve. Summary of Test Method 8. The cumulative volume of solution added is plotted against the observed pH values.
All pH measurements are made electrometrically. Similarly, the development of a precipitate during titration may ashm the glass electrode sluggish and cause high results. NOTE 1—Sulfuric acid of similar normality may be used instead of hydrochloric acid. Prepare and standardize in like manner.
Place the electrodes in the beaker and standardize the pH meter, using a reference buffer having a pH approximating that expected for the sample see Test Methods D Hold the tip of the pipette near the bottom of the beaker while discharging the sample. After each addition, mix the solution thoroughly. Determine the pH when the mixture has reached equilibrium as indicated by a constant 2 6 Reagent Chemicals, American Chemical Society Speci? Under the allowances made in 1.
Summary of Test Method Astmm solids may interfere in electrometric titrations by making the glass electrode sluggish. Waste materials present in some waters may interfere chemically with color titrations by destroying the indicator.
Variable results may be experienced with waters containing oxidizing or reducing substances, depending on the equilibrium conditions and the manner in which the sample is handled. Dilute to mL with water. To this solution add 0. Mechanical stirring, preferably of the magnetic type, is required for this operation; mixing by means of a gas stream is not permitted. Continue the titration until the necessary data for the titration curve have been obtained.
NOTE 2—If the sample requires ast, more than d106 mL of standard solution for its titration, use a 0. NOTE 3—An electrometric titration curve is smooth, with the pH changing progressively in a single direction, if equilibrium is achieved after each incremental addition of titrant, and may contain one or more in?
Ragged or irregular curves may indicate that equilibrium was not attained before adding succeeding increments. The time required will vary with different waters as the reaction rate constants of different chemical equilibria vary. In some instances the reaction time may be an interval of a few seconds while other slower, more complex reactions may require much longer intervals.
It is important, therefore, that the period be sufficient to allow for any signi? The acidity or alkalinity relative to a particular pH may be determined from the curve.
Precision and Bias 7 D — 068 and dissolve. Dilute to 1 L with water. This indicator is available commercially in prepared form. Hold the tip of the pipette near the bottom of the container while discharging the sample. Asstm using an indicator, add 0.
Add the standard solution in small increments, swirling the?
ASTM D – 16 Standard Test Methods for Acidity or Alkalinity of Water
As the end point is approached, a momentary change in color will be noted in that portion of the sample with which the reagent? From that point on, make dropwise additions. NOTE 5—The choice of end point will have been made to provide optimum data for the intended use or disposition of the water. When an indicator is used, those listed in Color change and endpoint data for indicators listed herein are presented in Appendix X2 and Table X2. NOTE 6—After some practice, slightly more or less indicator may be preferred.
The analyst must use the same quantity of phenolphthalein at all times, however, because at a given pH, the intensity of one-color indicators depends on the quantity. In many instances, the concentration of ferrous iron is such that a 2-min boiling period is not sufficient to assure complete oxidation.
In this test method, hydrogen peroxide is added prior to boiling to accelerate the chemical reactions needed for equilibrium. D — 06 Standard acid is added as needed to lower the pH to 4. Hydrogen peroxide H2O2 is added, the solution boiled, and? Suspended solids may cause sluggishness in electrometric titrations; however, compensation is made by a s pause between alkali additions or by dropwise addition of titrant when the designated pH is approached.
ASTM D1067 – 16
NOTE 8—Hydrochloric acid of similar normality may be used instead of sulfuric acid. NOTE 9—Minus acidity represents excess alkalinity contributed by constituents such as bicarbonates. The matrix and chemistry of the solution should be equivalent to the solution 5 If the pH is above 4. If the sample is colorless, titrate to the phenolphthalein color change while hot. Each replicate must be taken through the complete analytical test method including any sample pretreatment steps.
The replicates may be interspersed with samples. This study should be repeated until the recoveries are within the limits given in 15,24, or If a concentration other than the recommended concentration is used, refer to Test Method D for information on applying the F test and t test in evaluating the acceptability of the mean and standard deviation.
If large numbers of samples are analyzed in the bath, analyze the LCS after every 10 samples. The LCS must be taken through all of the steps of the analytical method, including sample pretreatment. The concentration of the IRM should be in the concentration mid-range for the method chose. The value obtained must fall within the control limits established by the laboratory. In water analysis, a pH of about 4. All the effects due to these anions are lumped together in an alkalinity analysis.
Acidic materials encountered in water analysis include, in addition to free organic and mineral acids, uncombined dissolved gases, and acids formed on hydrolysis of salts of weak bases and strong acids. Hydrolyzable salts of aluminum and ferric and ferrous iron in mine drainage and certain industrial waste waters, are common causes of wstm.
Acidity determinations on waters containing ferrous iron are further complicated by air oxidation of ferrous to the ferric state and subsequent hydrolysis to produce additional acidity. Interpretation of acidity and alkalinity data should be made cautiously.
For a more thorough understanding of the subject, it is recommended that the analyst review the literature9,10, Then, the analyst astmm be able to develop an interpretation of his data better suited to his particular needs. Under such conditions, all ferrous iron is rapidly oxidized to the ferric state, d10677 in the precipitation of Fe OH 3: First, the solubility of ferrous ion at a pH of 8.
Second, at a pH of 8. Subsequent hydrolysis of the resultant ferric d1076 immediately During the subsequent titration, the ferric ion is precipitated as ferric hydroxide: It is particularly applicable to mine drainage, industrial waste waters carrying waste acids, and similar waters.