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.
Highlights
The quantification of a reagent produced in an electrolysis cell without direct monitoring of charge is well known [5]. is work includes early research on estimating the charge passing through the cell from measuring the mass of silver deposited on the platinum electrode
From the mass change experienced by the cell, the amount of known amount of potassium hydrogen phthalate (KHP) can be determined to assess the stoichiometric relations between the electrolytic products of water
The feasibility of using an electrolysis cell for quantification of the electrolytic products of water from gravimetric measurement was tested. e cell presented in this paper enables in situ production of reagents and their direct quantification and does not require standardization of reagents. e electrolysis cell directly powered by 9 V batteries eliminates the requirement of a constant current source or a coulometer, yet offers advantages of coulometric method of titration. e cell utilizes minimal volume of reagents (3.2 mL or less in each compartment). e electrolysis cell is simple, transparent, and easy to fabricate. e cell eliminates the requirement of an external salt bridge or a fritted glass membrane
Summary
The quantification of a reagent produced in an electrolysis cell without direct monitoring of charge is well known [5]. is work includes early research on estimating the charge passing through the cell from measuring the mass of silver deposited on the platinum electrode [18, 19]. When a known quantity of KHP (a primary standard substance) is added to the cathode compartment, the endpoint of the neutralization reaction between electrolytically produced OH−(aq) and KHP can be determined visually with use of phenolphthalein as an indicator. From the mass change experienced by the cell, the amount of KHP can be determined to assess the stoichiometric relations between the electrolytic products of water.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
