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Pourbaix diagram of iron. [1] The Y axis corresponds to voltage potential. In electrochemistry, and more generally in solution chemistry, a Pourbaix diagram, also known as a potential/pH diagram, E H –pH diagram or a pE/pH diagram, is a plot of possible thermodynamically stable phases (i.e., at chemical equilibrium) of an aqueous electrochemical system.
The pH range is commonly given as zero to 14, but a pH value can be less than 0 for very concentrated strong acids or greater than 14 for very concentrated strong bases. [2] The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. [3]
To use potentiometric (e.m.f.) measurements in monitoring the + concentration in place of readings, one can trivially set [+] = and apply the same equations as above, where is the offset correction /, and is a slope correction / (1/59.2 pH units/mV at 25°C), such that replaces .
This shows that the absorbance values on the plot are offset by an equal amount and the slope of the two plots are equal. Thus, the concentration calculated from the two plots is equal. Other scalar components that contribute to the absorbance of a given sample like contaminants on the cuvette or a different cuvette material also are averaged ...
A pH meter is a scientific instrument that measures the hydrogen-ion activity in water-based solutions, indicating its acidity or alkalinity expressed as pH. [2] The pH meter measures the difference in electrical potential between a
PH or P/H: precipitation hardening, precipitation-hardened; pilot hole PHR BRZ: phosphor bronze PL or P/L: parts list: A list, usually tabular and often on the drawing (if not accompanying the drawing on a separate sheet), listing the parts needed in an assembly, including subparts, standard parts, and hardware.
The format defines the math for three functions: Slope, Offset and Power. Each function uses a number for the red, green, and blue color channels for a total of nine numbers comprising a single color decision. A tenth number, Saturation, specified in the Version 1.2 release, applies to the R, G, and B color channels in combination.
The slope of the phreatic surface is assumed to indicate the direction of groundwater movement in an unconfined aquifer. The phreatic zone , below the phreatic surface where rock and soil are saturated with water, is the counterpart of the vadose zone , or unsaturated zone, above.