Teaching pH Measurements with a Student-Assembled Combination Quinhydrone Electrode

Abstract

A combination pH electrode that can be assembled by the student is described. It consists of a glass holder and two sensors in the form of rubber stoppers that contain quinhydrone and graphite. The combination electrode is suitable to teach potentiometric measurements, pH measurements, and the interplay of acid–base and redox equilibria. The electrode meets highest safety standards and overcomes the troubles associated with the use of the conventional quinhydrone electrode. Compared with commercial combination glass electrodes, the combination quinhydrone electrode has the didactic advantage that the sensor and the reference electrodes are both visible and not preassembled.

Producción de hidrógeno a partir de energía solar. Panorama en Colombia

“…También es posible emplear la energía eléctrica generada por un sistema de concentración solar para llevar a cabo electrólisis de alta temperatura, cuya ventaja es un menor requerimiento de energía eléctrica. La electrólisis, es el proceso principal de estos sistemas y consiste en la reacción electroquímica que separa la molécula del agua en hidrógeno y oxígeno, mediante la aplicación de un voltaje o corriente eléctrica generalmente de tipo continua que promueve las reacciones de óxido-reducción [37], [38]. El costo de la producción de hidrógeno mediante electrólisis a partir de energía solar fotovoltaica, es elevado, dado que la relación entre el volumen de hidrógeno generado, por superficie de sistemas fotovoltaicos de escala comercial, es baja.…”

Simple and Economical Procedure To Assemble pH Glass Membrane Electrodes Used in Chemical Education

“…In chemistry education, the pH measurement of solutions can be performed in introductory level experiments. However, the content of such courses generally concentrates on the operation of using commercial pH electrodes as the electrochemical sensor, which partly weakens the learning opportunities with respect to ion-selective electrodes and the Nernst equation …”

“…In recent years, many different self-made electrodes have been reported in the literature. − The preparation of these electrodes usually follows an effective and convenient method. For example, Goldcamp et al designed an inexpensive and disposable pH electrode by the assembly of a liquid membrane .…”

“…However, the content of such courses generally concentrates on the operation of using commercial pH electrodes as the electrochemical sensor, which partly weakens the learning opportunities with respect to ion-selective electrodes and the Nernst equation. 11 In recent years, many different self-made electrodes have been reported in the literature. 11−19 The preparation of these electrodes usually follows an effective and convenient method.…”

Practical pH Measurement and Theoretical Approach: Acid-Base System

“…Usually instrumental methods are considered more reliable than classical methods but in some cases instrumental techniques also get fail. Previous reports are based on uses and construction of electrodes extensively [1,2,3,4] but don't emphasize on simple experiment by which a student can learn and understand better about these electrodes. A laboratory experiment is needed to be designed for students in this context to make them understand when they switch from classical method to instrumental one and to teach them better about the deviation of practical pH measurement from theoretical approach for a dilute acid/base system.…”