Chemically equivalent temperature

Under conditions where the rotation about the C-N bond of dimethylformamide is slow relative to the NMR time scale, the two methyl resonances will be separate singlets. Conversely, if the rotation is made to be very fast, the two methyl groups will be chemically equivalent. Their resonance will then appear as a sharp singlet. In between these extremes, kinetic information can be extracted from the line shapes. In most systems the parameter that is changed to go between these limits is the temperature. In some systems, pH or pressure has the same effect. 

At ambient temperatures, the primary CV processes observed for Co2(CO)6 2 ifi-T] ijL-ri -RC2C2R) (R = Ph, Fc), which contain two chemically equivalent C02 (/z-alkyne)(CO)6 redox centers, are an apparent irreversible 2-e reduction, with an... 

Table 16. Fractional atomic coordinates, equivalent temperature factors and final anisotropic chemical parameters (with e.s.d. s in parentheses) for compound (III)...

Rellstab found that if the time of transpiration of chemically equivalent amounts of liquids at temperatures of equal vapour pressure are compared, these increase in homologous series. Isomeric substances usually have different times of efflux, but the difference is less when they have similar boiling points. Substances containing double bonds have larger transpiration times than those of equal molecular weight containing only singly linked carbon. 

AG is considered negative. AG° for the burning of graphite under standard temperature (25°C) and pressure (1 atm), indicated by the superscript °, is -394.4kJ mol-1. Tables of AG° for various reactions are widely available and values of AG° for different reactions can be calculated by simple arithmetic combination of tabulated values. Any reaction with a negative AG value will in theory proceed spontaneously—the chemical equivalent of water flowing downhill —releasing energy. 

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