Stefano Stefano   39-08-02 00:00 (0) 대체로 화공엔지니어들은 분석화학에 약합니다. 따라서 이곳에서 만족스러운 답을 듣지 못했다 해서 너무 서운히 생각하지 말아주셨으면 합니다. (1) 우선 다음 출처에서의 자료를 참고해 보세요. (Ref:http://www.laboratorytalk.com/news/sti/sti102.html) A thermometric titrimetric method has been developed for the determination of the individual components in a mixture comprising phosphoric, nitric, and acetic acids. The method involves two separate titrations. The first determination involves the titration of the mixed acids with standard sodium hydroxide solution. Two sharp endpoints are obtained; the first resulting from the combined protons from the nitric acid and the first proton of the phosphoric acid. The second endpoint represents the combined proton from the acetic acid and the second proton of the phosphoric acid. There is also a broader, third endpoint for the third proton of phosphoric acid, but this is non-stoichiometric. In the second titration the acid mixture is strongly basified with aqueous ammonia solution, and titrated with magnesium nitrate solution. The reaction enthalpy of the formation of insoluble magnesium ammonium phosphate provides the basis for a very sharp endpoint. To calculate the amount of nitric and acetic acids, the amount of phosphoric acid is expressed as a volume of standard sodium hydroxide solution, and subtracted from the titres for the first and second endpoints respectively in the acid/base titration. Calculations may be performed in a dedicated spreadsheet linked to the titration software. This method may be fully automated to run the two titrations as a single contiguous sequence, and is suitable for routine operation in a process control laboratory. Precision (one standard deviation) for the determination of phosphoric acid is 0.04%w/v, while that of nitric and acetic acids is 0.2% and 0.1%w/v respectively. (2)욧점은 질산과 인산의 첫프로톤이 함께 나타내는 산도(A)를 가성소다용액으로 적정하고, 이어서 인산의 두번째 프로톤과 초산이 함께 나타내는 산도(B)를 구한다음, 별도의 시료를 이용해서 암모니아로 완전히 알카리성으로 만든 후 이를 질산 마그네시움용액으로 적정하여 인산이 나타내는 산도(C)를 구하면 Total Acidity(T) = 질산과 인산1차프로톤의 혼합 산도(A) + 인산 2차프로톤과 초산의 혼합산도 (B) ....(1)이 되고 (인산의 함량) = C ---------------(2) (질산의 함량) = A - C -----------(3) (초산의 함량) = B - C -----------(4) 로 계산할 수 있다는 설명입니다. (2)적정시 A와 B는 pH의 급격한 변화를 이용해서 당량점을 찾지만 C는 열량분석을 이용해서 당량점을 찾는 다는 것이 윗 인용부분의 욧점입니다. 힌트가 되었다면 다행입니다.  (0) 대체로 화공엔지니어들은 분석화학에 약합니다. 따라서 이곳에서 만족스러운 답을 듣지 못했다 해서 너무 서운히 생각하지 말아주셨으면 합니다. (1) 우선 다음 출처에서의 자료를 참고해 보세요. (Ref:http://www.laboratorytalk.com/news/sti/sti102.html) A thermometric titrimetric method has been developed for the determination of the individual components in a mixture comprising phosphoric, nitric, and acetic acids. The method involves two separate titrations. The first determination involves the titration of the mixed acids with standard sodium hydroxide solution. Two sharp endpoints are obtained; the first resulting from the combined protons from the nitric acid and the first proton of the phosphoric acid. The second endpoint represents the combined proton from the acetic acid and the second proton of the phosphoric acid. There is also a broader, third endpoint for the third proton of phosphoric acid, but this is non-stoichiometric. In the second titration the acid mixture is strongly basified with aqueous ammonia solution, and titrated with magnesium nitrate solution. The reaction enthalpy of the formation of insoluble magnesium ammonium phosphate provides the basis for a very sharp endpoint. To calculate the amount of nitric and acetic acids, the amount of phosphoric acid is expressed as a volume of standard sodium hydroxide solution, and subtracted from the titres for the first and second endpoints respectively in the acid/base titration. Calculations may be performed in a dedicated spreadsheet linked to the titration software. This method may be fully automated to run the two titrations as a single contiguous sequence, and is suitable for routine operation in a process control laboratory. Precision (one standard deviation) for the determination of phosphoric acid is 0.04%w/v, while that of nitric and acetic acids is 0.2% and 0.1%w/v respectively. (2)욧점은 질산과 인산의 첫프로톤이 함께 나타내는 산도(A)를 가성소다용액으로 적정하고, 이어서 인산의 두번째 프로톤과 초산이 함께 나타내는 산도(B)를 구한다음, 별도의 시료를 이용해서 암모니아로 완전히 알카리성으로 만든 후 이를 질산 마그네시움용액으로 적정하여 인산이 나타내는 산도(C)를 구하면 Total Acidity(T) = 질산과 인산1차프로톤의 혼합 산도(A) + 인산 2차프로톤과 초산의 혼합산도 (B) ....(1)이 되고 (인산의 함량) = C ---------------(2) (질산의 함량) = A - C -----------(3) (초산의 함량) = B - C -----------(4) 로 계산할 수 있다는 설명입니다. (2)적정시 A와 B는 pH의 급격한 변화를 이용해서 당량점을 찾지만 C는 열량분석을 이용해서 당량점을 찾는 다는 것이 윗 인용부분의 욧점입니다. 힌트가 되었다면 다행입니다.