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Feasibility of Using an Electrolysis Cell for Quantification of the Electrolytic Products of Water from Gravimetric Measurement

Author:
Melaku, Samuel, Gebeyehu, Zewdu, Dabke, Rajeev B.
Source:
Journal of Analytical Methods in Chemistry (Online) 2018 v.2018
ISSN:
2090-8873
Subject:
anodes, batteries, carbon dioxide, cathodes, color, electrolysis, gravimetry, hydrogen, ions, neutralization, oxygen, phthalates, potassium bicarbonate, protons, vinegars
Abstract:
A gravimetric method for the quantitative assessment of the products of electrolysis of water is presented. In this approach, the electrolysis cell was directly powered by 9 V batteries. Prior to electrolysis, a known amount of potassium hydrogen phthalate (KHP) was added to the cathode compartment, and an excess amount of KHCO₃ was added to the anode compartment electrolyte. During electrolysis, cathode and anode compartments produced OH⁻(aq) and H⁺(aq) ions, respectively. Electrolytically produced OH⁻(aq) neutralized the KHP, and the completion of this neutralization was detected by a visual indicator color change. Electrolytically produced H⁺(aq) reacted with HCO₃⁻(aq) liberating CO₂(g) from the anode compartment. Concurrent liberation of H₂(g) and O₂(g) at the cathode and anode, respectively, resulted in a decrease in the mass of the cell. Mass of the electrolysis cell was monitored. Liberation of CO₂(g) resulted in a pronounced effect of a decrease in mass. Experimentally determined decrease in mass (53.7 g/Faraday) agreed with that predicted from Faraday’s laws of electrolysis (53.0 g/Faraday). The efficacy of the cell was tested to quantify the acid content in household vinegar samples. Accurate results were obtained for vinegar analysis with a precision better than 5% in most cases. The cell offers the advantages of coulometric method and additionally simplifies the circuitry by eliminating the use of a constant current power source or a coulometer.
Agid:
6240052