Resumo
For the determination of exchangeable hydrogen ion in soils, the authors of the presente work made the extraction with normal calcium acetate solution that may have an initial pH between 7 and 8 without altering the amount of hydrogen ion extracted. The extraction was made by shaking 5,0 grams of air dry soil with 100 ml of normal calcium acetate solution, the pH of wich was ascertained to 7,0, 7,5 and 8,0 with acetic acid, in 250 mil conical flasks for 30 minutes in a Wagner shaker (30-40 rpm). The contents of the flasks were then, filtered. A 50 ml aliquot of each of the leachate was titrated with a 0,020 N NaOH solution and the volumes consumed sodium hydroxide were ploted against pH. The titration curves thus obtained showed to be straight lines between pH 8 and 9 and parallel to the curve obtained by the titration of the blank. Two ways of locating the end point of the titration showed to be possible: the use of a pHmeter or titrimeter or the use of phenolphtalein as indicator. When using a pH meter or a titrimeter, the end point may rest in any point between pH 8 and 9, and the volume of sodium hydroxide consumed is found by comparison with a similar curve obtained by the titration of the blank. When using phenolphtalein the calcium acetate solution must have a pH below 8.
O método potenciométrico na determinação do H+ trocável em solos* * Trabalho realizado com aparelhos doados pela Fundação Rockefeller.
H. Bergamin FilhoI; R. A. CataniI; H. Petrin JuniorII
IE. S. A. «Luiz de Queiroz»
IITerceiranista da ESALQ
SUMMARY
For the determination of exchangeable hydrogen ion in soils, the authors of the presente work made the extraction with normal calcium acetate solution that may have an initial pH between 7 and 8 without altering the amount of hydrogen ion extracted.
The extraction was made by shaking 5,0 grams of air dry soil with 100 ml of normal calcium acetate solution, the pH of wich was ascertained to 7,0, 7,5 and 8,0 with acetic acid, in 250 mil conical flasks for 30 minutes in a Wagner shaker (30-40 rpm). The contents of the flasks were then, filtered.
A 50 ml aliquot of each of the leachate was titrated with a 0,020 N NaOH solution and the volumes consumed sodium hydroxide were ploted against pH. The titration curves thus obtained showed to be straight lines between pH 8 and 9 and parallel to the curve obtained by the titration of the blank.
Two ways of locating the end point of the titration showed to be possible: the use of a pHmeter or titrimeter or the use of phenolphtalein as indicator.
When using a pH meter or a titrimeter, the end point may rest in any point between pH 8 and 9, and the volume of sodium hydroxide consumed is found by comparison with a similar curve obtained by the titration of the blank.
When using phenolphtalein the calcium acetate solution must have a pH below 8.
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BIBLIOGRAFIA
CATANI, R. A., J. R. GALLO, 1955 - Avaliação da exigência em calcário dos solos do Estado de S. Paulo, mediante correlação entre o pH e a porcentagem de saturação em bases. Rev. Agr. Piracicaba - 30:49-60.
CATANI, R. A., J. R. GALLO, H. GARGANTINI, 1955 - Amostragem de solo, métodos de análise, interpretação e indicações gerais, para fins de fertilidade. Inst. Agr. Campinas, Boletim n.º 69. 28 pp.
JACKSON, M. L., 1958 - Soil Chemical Analysis. 28 pp. Prentice Hall. Inc. N. J.. 498 pp.
MAEHL, K. A., 1940 - Potentiometric Determination of Exchangeable Hydrogen in Unsatured Soils - Ind. Eng. Chem. Anal. Ed. 12:24-27.
MEHLICH, A., 1945 - Effect of Type of Soil Colloid on Cation Adsortion Capacity and on Exchangeable Hydrogen and Calcium as Measured by different Methods. Soil Sci. 60:289-305.
PARKER, F. W. - 1929 - The Determination of Exchangeable Hydrogen in Sils. J. Am. Soc. Agron. 21:1030-1039.
SILVA, A. COELHO DA, 1957 - Determinação potenciométrica do Hidrogênio permutável dos solos. Bol. n.º 52 Inst. Quím. Agric. - Rio de Janeiro - 16 pp.
SCHOLLENBERGER, C.S., 1927 - Exchangeable Hydrogen and Soil reaction. Soil Sci. 65: 552-553. VETTORI, L., 1948 - Determinação da necessidade de cal dos solos. Bol. n.º 7 Inst. Quim. Agric. - Rio de Janeiro 19 pp.
Recebido para publicação em 15/10/60.
- CATANI, R. A., J. R. GALLO, 1955 - Avaliação da exigência em calcário dos solos do Estado de S. Paulo, mediante correlação entre o pH e a porcentagem de saturação em bases. Rev. Agr. Piracicaba - 30:49-60.
- CATANI, R. A., J. R. GALLO, H. GARGANTINI, 1955 - Amostragem de solo, métodos de análise, interpretação e indicações gerais, para fins de fertilidade. Inst. Agr. Campinas, Boletim n.ş 69. 28 pp.
- JACKSON, M. L., 1958 - Soil Chemical Analysis. 28 pp. Prentice Hall. Inc. N. J.. 498 pp.
- MAEHL, K. A., 1940 - Potentiometric Determination of Exchangeable Hydrogen in Unsatured Soils - Ind. Eng. Chem. Anal. Ed. 12:24-27.
- MEHLICH, A., 1945 - Effect of Type of Soil Colloid on Cation Adsortion Capacity and on Exchangeable Hydrogen and Calcium as Measured by different Methods. Soil Sci. 60:289-305.
- PARKER, F. W. - 1929 - The Determination of Exchangeable Hydrogen in Sils. J. Am. Soc. Agron. 21:1030-1039.
- SILVA, A. COELHO DA, 1957 - Determinação potenciométrica do Hidrogênio permutável dos solos. Bol. n.ş 52 Inst. Quím. Agric. - Rio de Janeiro - 16 pp.
- SCHOLLENBERGER, C.S., 1927 - Exchangeable Hydrogen and Soil reaction. Soil Sci. 65: 552-553.
- VETTORI, L., 1948 - Determinação da necessidade de cal dos solos. Bol. n.ş 7 Inst. Quim. Agric. - Rio de Janeiro 19 pp.
Datas de Publicação
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Publicação nesta coleção
10 Set 2012 -
Data do Fascículo
1960
Histórico
-
Recebido
15 Out 1960
