Standard electric tension

In the spirit of the Stockholm recommendation we may consider d as equal to the electrode potential of the Zn/Za electrode for the case of zero current. Actually the electric tension of cell (56) is always, with and without current, that of the Zn/Zn electrode taken from metal to solution relatively to the conventionally selected standard hydrogen electrode. 

Standard Electric and Chemical Tensions of Electrodes or Couples... 

The National Electrical Manufacturers Association (NEMA) has developed a standard that specifies minimum pulley diameters that should be used on electric motors. Since motor bearings are specified using a relatively small maximum overhung load, minimum pulley diameters can have a dramatic effect on motor bearings. The increase in tension that is created by smaller pulleys can transmit a potentially destructive side-load on the bearings. 

The National Institute of Standards and Technology (NIST) molten salts database has been designed to provide engineers and scientists with rapid access to critically evaluated data for inorganic salts in the molten state. Properties include density, viscosity, electrical conductance, and surface tension. Properties for approximately 320 single salts and 4000 multicomponent systems are included, the latter being primarily binary. Data have been abstracted from the literature over the period 1890-1990. The primary data sources are the National Bureau of Standards-National... 

The molten salt standard program was initiated at Rensselaer Polytechnic Institute (RPI) in 1973 because of difficulties being encountered with accuracy estimates in the NBS-NSRDS molten salt series. The density, surface tension, electrical conductivity, and viscosity of KNO3 and NaCl were measured by seven laboratories over the world using samples distributed by RPI. The data from these round-robin measurements of raw properties were submitted to RPI for evaluation. Their recommendations are summarized in Table 2. 

G. J. Janz, J. Phys. Chem. Ref Data 9 (1980) 791 Molten Salts Data as Reference Standards for Density, Surface Tension, viscosity and Electrical Conductance KN03 and NaCl, American Chemical Society-American Institute of Physics-National Bureau of Standards, Washington, DC, 1980. 

Electric Effects. The science of electrocapillarity exists for over 100 years. When a liquid surface is electrically charged, its tension changes, and these changes can be followed quantitatively with the standard methods of measuring 7. It is tempting to apply the notions of electrocapillarity to solid surfaces, and a recent book162) is a particularly rich example. 

Bright, silvery-white metal face-centered cubic crystal structure (a = 0.5582 nm) at ordinary temperatures, transforming to body-centered cubic form (a= 0.4407) at 430°C density 1.54 g/cm at 20°C hardness 2 Mohs, 17 Brinnel (500 kg load) melts at 851°C vaporizes at 1,482°C electrical resistivity 3.43 and 4.60 microhm-cm at 0° and 20°C, respectively modulus of elasticity 3-4x10 psi mass magnetic susceptibility -i-1.10x10 cgs surface tension 255 dynes/cm brick-red color when introduced to flame (flame test) standard reduction potential E° = -2.87V... 

Mercury has a high density (13.546 g cm" at 20 °C) and a wide liquid range (mp -38.9 °C bp 357) over most of which its volume expands uniformly. In addition, the high surface tension of mercury keeps it from sticking to glass surfaces. These properties have contributed to its use in an impressive number of laboratory applications. For a metal, mercury has an unusually high electrical resistivity or specific resistance (95.8 J,S2 cm), and this property enables it to be used as an electrical standard. Of all the common metals, only bismuth has a higher resistivity. 

Salinity defines the concentration of ions dissolved in soil water, and is measured directly by electrical conductivity (EC). Soil water is held under tension or suction and as such is not available for analysis. To compensate for this, the standard procedure is to measure soil EC on a water extract. Soil scientists use what is called a saturated paste soil water extract (for more details see Radojevic and Bashkin, 1999). 

References (i) Janz, G.J. (1967) Molten Salts Handbook. Academic Press, New York (ii) Lovering, D.G and Gale, R.J. (1983,1984, and 1990) Molten Salts Techniques, Vol. 1, 2, i and 4. Plenum Press, New York, (iii) Janz, G.J. (1988) Thermodynamic and Transport Properties for Molten Salts Correlation equations for critically evaluated density, surface tension, electrical conductance and viscosity data. Journal of Physical and Chemical Refrence Data. Vol. 17, Supplement 2, Published jointly by the American Chemical Society (ACS), the American Institute of Physics (AIP), and the National Bureau of Standards (NBS) and (iv) Barin, I., and Knacke, O. (1973) Thermodynamical Properties of Inorganic Substances. 

Shrinkage. Standard pet and PEN films from the stenter process will shrink between 1 and 3% at temperatures above the Tg. For the high level of accuracy required by some electrical applications shrinkages of below 0.1-0.2% are required. In order to meet this the film is unwoimd and passed through a carefully temperature-controlled oven, with almost no tension in the film. The amount of residual shrinkage in the film after this process is typically less than 0.1% in the MD and the TD for temperatures up to 150°C for PET and 200°C for PEN. 

We have carried out a series of measurements with water suspensions of PSL spheres seeded with TFA. The spheres were supplied by Duke Scientific as calibrated size standards with nominal diameters as shown in Table I, and with an unknown standard deviation. The table shows also the electrical conductivity of the corresponding solutions as well as the ratio between dmin from equation 3 and the nominal sphere diameter. All the solutions were electrosprayed into CO2 because the high surface tension of water requires large voltages for the cone-jet to set in, which tends to produce electrical breakdown when the gas is air (26, 19), The aerosol is sampled from the spray region and passed through the DMA. This instrument operates in such a way that the exiting aerosol is carried in dry air, and its selected mobility corresponds neaiiy to that in air rather than in CO2. 

The 18 selected properties were atomic mass (A), density (d), atomic radius (r), first (II), second (12) and third (13) ionization energy, Pauling electronegativity (X), melting point (MP), boiling point (BP), enthalpy of fusion (HF), vaporization (ITV), atomization (HA), standard entropy (S), specific heat capacity (SHC), surface tension (ST) at the melting point, electrical resistivity (ER), heat conductivity (HC), and the formation free energy of the chloride Ends per mol of Cl (FFE)—as a characteristic of chemical reactivity. 

FIGURE 5.3 Types S and L tension-impact specimens. (Dimensions in inches.) (From Tensile Impact Energy to Break Plastics and Electrical Insulating Materials, ASTM Standard D1822, West Conshohocken, PA, 1999. Copyright ASTM International. Reprinted with permission.)... 

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