서강대 기기분석실험 &lt; Constant-current coulometry &gt; 레포트

서강대 기기분석실험 < Constant-current coulometry > 레포트

문서 내 토픽

1. Coulometric titration

Coulometric titration은 전기 분해 시 생성되는 전하량을 이용하여 물질의 양을 정량 분석하는 방법이다. 전위를 일정하게 유지하는 constant potential 방법과 전류를 일정하게 유지하는 constant current 방식이 있다. 이번 실험에서는 constant current 방식을 이용하여 As3+의 titration을 진행하였다.
2. Iodine-starch reaction

Iodine-starch reaction은 녹말이 아이오딘으로 인하여 반응이 시작되고 일정 시간이 경과한 후 투명했던 용액의 색이 청색으로 변화하는 반응이다. 이 반응은 clock reaction의 예로, 3단계의 반응이 요구된다. 이번 실험에서는 녹말을 지시약으로 사용하여 종말점을 찾았다.
3. Faraday's law

전기 분해 시 전극에 흐르는 전하량과 화학 변화량 사이의 정량적 관계를 나타내는 패러데이 법칙을 이용하여 As의 양을 정량분석하였다. 패러데이 1법칙은 석출되는 물질의 질량은 전극을 통과한 전자의 몰수에 비례한다는 것이고, 2법칙은 같은 전기량에 의하여 석출된 물질의 질량은 화학종에 무관하게 화학 당량에 비례한다는 것이다.

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1. Coulometric titration

Coulometric titration is a powerful analytical technique that has numerous applications in various fields, including chemistry, electrochemistry, and environmental analysis. This method relies on the controlled electrochemical generation of a titrant species, which is then used to quantify the analyte of interest. The key advantage of coulometric titration is its high accuracy and precision, as the amount of titrant generated is directly proportional to the electric charge passed during the electrochemical reaction, which can be measured with great precision. Additionally, coulometric titration is often preferred over traditional volumetric titration methods because it requires smaller sample sizes and can be automated, making it more efficient and less prone to human error. Furthermore, coulometric titration can be used to determine the concentration of species that are difficult to titrate using other methods, such as those that are poorly soluble or have slow reaction kinetics. Overall, coulometric titration is a versatile and reliable analytical tool that continues to be widely used in both research and industrial settings.
2. Iodine-starch reaction

The iodine-starch reaction is a classic and widely used analytical technique in chemistry. This reaction is based on the formation of a deep blue-black complex between iodine and starch, which serves as a highly sensitive and specific indicator for the presence of iodine. The iodine-starch complex is formed when iodine molecules penetrate the helical structure of the starch polymer, creating a distinctive color change that can be easily observed and quantified. This reaction has numerous applications, including the detection and quantification of iodine in various samples, the determination of starch content in food and agricultural products, and the monitoring of redox reactions in which iodine is involved. Additionally, the iodine-starch reaction is often used as a visual indicator in titration experiments, where the disappearance or appearance of the blue-black color can be used to determine the endpoint of the titration. Overall, the iodine-starch reaction is a simple, yet powerful analytical tool that continues to be widely used in both research and practical applications.
3. Faraday's law

Faraday's laws of electrolysis are fundamental principles in electrochemistry that describe the quantitative relationship between the amount of a substance produced or consumed at an electrode and the amount of electric charge passed through the electrochemical cell. The first law states that the mass of a substance produced or consumed at an electrode is directly proportional to the amount of electric charge passed through the cell, while the second law states that the mass of different substances produced or consumed at an electrode is proportional to their chemical equivalents. These laws have far-reaching implications in various fields, including electroplating, electrochemical energy storage and conversion, and analytical chemistry. Faraday's laws provide a solid theoretical foundation for understanding and predicting the behavior of electrochemical systems, and they have been extensively validated through experimental observations. The application of Faraday's laws has led to the development of numerous electrochemical techniques, such as coulometry and electroanalytical methods, which are widely used in research, industry, and environmental monitoring. Overall, Faraday's laws are essential concepts in electrochemistry that continue to be of great importance in both theoretical and practical aspects of the field.