Direct Determination of Gas pH and Carbon Dioxide Concentration with pH Electrodes

A simple apparatus to measure gas pH and carbon dioxide (CO2) concentration was designed for undergraduate students in the analytical chemistry laboratory. Gas passed through a flow meter and a mixer, then reached the homemade measuring chamber and caused the potential change of a pH combination ele...

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Bibliographic Details
Published in:Journal of chemical education 2014-04, Vol.91 (4), p.593-596
Main Authors: Yang, Qinlan, Long, Jun, Zheng, Hao, Tian, Xianqing, Lei, Dean, Zhu, Xiaoqiong, Guo, Yong, Xiao, Dan
Format: Article
Language:English
Subjects:
Analytical chemistry
Aqueous solutions
Carbon dioxide
Carbon dioxide concentration
Chromatography
College students
Electrodes
Gas sampling
Hygroscopicity
Motion pictures
Organic chemistry
Polyethylene glycol
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Summary:A simple apparatus to measure gas pH and carbon dioxide (CO2) concentration was designed for undergraduate students in the analytical chemistry laboratory. Gas passed through a flow meter and a mixer, then reached the homemade measuring chamber and caused the potential change of a pH combination electrode. Poly(ethylene glycol)-20000 aqueous solutions with hygroscopicity and nontoxicity were used as reaction media by forming absorption liquid films around the junction point and the bulb of the pH combination electrode. A laboratory-made voltage follower and a N2000 chromatography data system were used to transform impedance and record data, respectively. Gas samples containing 10–100% CO2 were measured with the apparatus, and fast potential responses for different concentrations of CO2 were obtained. This apparatus is more cost-effective and eco-friendly as compared with other conventional methods.
ISSN:0021-9584
1938-1328
DOI:10.1021/ed300867n