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Potentiometric solid state gas sensors have been generally classified into three broad groups. Type I sensors have an electrolyte containing mobile ions of the chemical species in the gas phase that it is monitoring. The commercial product, YSZ oxygen sensor, [1] is an example of type I.
For example, from Fe 2+ + 2 e − ⇌ Fe(s) (–0.44 V), the energy to form one neutral atom of Fe(s) from one Fe 2+ ion and two electrons is 2 × 0.44 eV = 0.88 eV, or 84 907 J/(mol e −). That value is also the standard formation energy (∆ G f °) for an Fe 2+ ion, since e − and Fe( s ) both have zero formation energy.
The type of oxygen sensor used in most underwater diving applications is the electro-galvanic oxygen sensor, a type of fuel cell, which is sometimes called an oxygen analyser or ppO 2 meter. They are used to measure the oxygen concentration of breathing gas mixes such as nitrox and trimix . [ 9 ]
where μ is the electric dipole moment of the effectively polarized water molecule (2.35 D for the SPC/E model), μ 0 is the dipole moment of an isolated water molecule (1.85 D from experiment), and α i is an isotropic polarizability constant, with a value of 1.608 × 10 −40 F·m 2. Since the charges in the model are constant, this ...
Dew drop on a hydrophobic leaf surface Cutting a water droplet using a superhydrophobic knife on superhydrophobic surfaces Water drops on the hydrophobic surface of grass. In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. [1] In contrast, hydrophiles are ...
Cloth, treated to be hydrophobic, shows a high contact angle. The theoretical description of contact angle arises from the consideration of a thermodynamic equilibrium between the three phases: the liquid phase (L), the solid phase (S), and the gas or vapor phase (G) (which could be a mixture of ambient atmosphere and an equilibrium concentration of the liquid vapor).
The most popular hydrophobicity scale was developed by measuring surface tension values for the naturally occurring 20 amino acids in NaCl solution. [30] The main drawbacks of surface tension measurements is that the broken hydrogen bonds and the neutralized charged groups remain at the solution air interface.
A glass electrode is a type of ion-selective electrode made of a doped glass membrane that is sensitive to a specific ion. The most common application of ion-selective glass electrodes is for the measurement of pH. The pH electrode is an example of a glass electrode that is sensitive to hydrogen ions.