Question

How do you convert the solution of the third old
into the solution of the first glass!​

Answer 1

Introduction

Glass electrodes sensitive to hydrogen ions are the most commonly used sensors in chemistry and related disciplines. They belong to the group of potentiometric membrane sensors and are constructed in various configurations, depending on the application. Their basic design and properties are described and discussed in this article. Among their important properties is the selectivity, which depends on the composition of the glass. Glass electrodes are used mainly for pH measurements, but they may compose a part of more sophisticated systems in gas sensors or enzymatic sensors. Recently glasses based on a nonsilica structure have been used in potentiometric measurements.

Ulrich J. Krull, Michael. Thompson, in Encyclopedia of Physical Science and Technology (Third Edition), 2003

Glass electrodes

Glass electrodes are ion-selective electrodes based on the chemical properties of a glass membrane of defined chemical composition. Alteration of the glass chemistry to contain variable quantities of Na2O, CaO, SiO2, and Al2O3 produces chemically active binding sites in the glass that have hydronium, sodium, or simple cation selectivity. The construction of a typical electrochemical cell based on a glass electrode is shown in Fig. 16, including a representation of the physical properties of the sensing membrane. The internal solution contains a fixed concentration of the cation of interest and therefore fixes the internal electrode surface potential, while that in the external solution varies. The electric potential develops only in each hydrated gel layer based on an ion-exchange principle that leads to a phase boundary potential. The entire glass membrane is nominally 50–100 μm in thickness, but the hydrated glass accounts for little of this, being only 5–100 nm thick. Conduction within the dry glass is due to the cation of lowest charge and is not related to penetration by a substantial amount of cations.