Gran Plot

A Gran plot (also known as Gran titration or the Gran method) is a common means of standardizing a titrate or titrant by estimating the equivalence volume or end point in a strong acid-strong base titration or in a potentiometric titration. Such plots have been also used to calibrate glass electrodes, to estimate the carbonate content of aqueous solutions, and to estimate the Ka values (acid dissociation constants) of weak acids and bases from titration data.

Gran plots use linear approximations of the a priori non-linear relationships between the measured quantity, pH or electromotive potential (emf), and the titrant volume. Other types of concentration measures, such as spectrophotometric absorbances or NMR chemical shifts, can in principle be similarly treated. These approximations are only valid near, but not at, the end point, and so the method differs from end point estimations by way of first- and second-derivative plots, which require data at the end point. Gran plots were originally devised for graphical determinations in pre-computer times, wherein an x-y plot on paper would be manually extrapolated to estimate the x-intercept. The graphing and visual estimation of the end point have been replaced by more accurate least-squares analyses since the advent of modern computers and enabling software packages, especially spreadsheet programs with built-in least-squares functionality.

Read more about Gran PlotBasis of The Calculations, Titrating Strong Acid With Strong Base, Titrating Strong Base With Strong Acid, Concentrations and Dissociation Constants of Weak Acids, Carbonate Content, Potentiometric Monitoring of H+, Electrode Calibration, Potentiometric Monitoring of Other Species, Non-ideal Behaviour

Other articles related to "gran plot, plots, gran":

Gran Plot - Non-ideal Behaviour
... before-equivalence and beyond-equivalence plots should ideally cross the x axis at the same point ... incomplete precipitation in potentiometric titrations of dilute solutions, for which Gran et al ... Because the or terms in the Gran functions only asymptotically tend toward, and never reach, the x axis, curvature approaching the equivalence point is to be ...

Famous quotes containing the word plot:

    But, when to Sin our byast Nature leans,
    The careful Devil is still at hand with means;
    And providently Pimps for ill desires:
    The Good Old Cause, reviv’d, a Plot requires,
    Plots, true or false, are necessary things,
    To raise up Common-wealths and ruine Kings.
    John Dryden (1631–1700)