Buffer Physical Constants

To interpolate a density or viscosity press the compute button on either the buffer density or buffer viscosity frames. The buffer components form will appear. The same form will toggle back and forth between density and viscosity calculations by pressing the density and viscosity buttons. Pressing OK will return the computed values from to the main form. Pressing Cancel will return to the main form without changing its state.

Choose buffer components from the list provided. You must not only choose the name, but also enter the concentration of the component in the text box. The concentration is entered in the Molarity text box which is highlighted immediately after a component is selected. Components entered mistakenly or with the wrong concentration may be removed with the remove button. After entering the buffer components, you may switch to viscosity or density to compute the other value using the same components in the buffer.

If a buffer component is not listed, the density and viscosity data has not yet been fit to the polynomial function Sednterp uses to interpolate these values. With experimental measurements, new components may be added to the database of interpolating polynomials.

The first step Sednterp uses to calculate the density of a buffer is to calculate the density of the buffer at 20 degrees C. Then, the density is corrected for temperature assuming that water is the predominant component in the buffer. While this is true for solutions containing moderate amounts of other components, significant errors may be introduced for solutions containing high solute concentrations. For such solutions at temperatures far from 20 C, the user is advised to compute the density and enter it manually.