[2] The methods involve changing the phase of the analyte to separate it in its pure form from the original mixture and are quantitative measurements.

The proper reagent, when added to aqueous solution, will produce highly insoluble precipitates from the positive and negative ions that would otherwise be soluble with their counterparts (equation 1).

Water eliminated in a quantitative manner from many inorganic substances by ignition is an example of a direct determination.

[6][7] Determination of the amount of water by measuring the loss in mass of the sample during heating is an example of an indirect method.

It is well known that changes in mass occur due to decomposition of many substances when heat is applied, regardless of the presence or absence of water.

The widened margin of error created by this all-too-often false assumption is not one to be lightly disregarded as the consequences could be far-reaching.

Heat can also be used, if oxygen is present, for combustion to isolate the suspect species and obtain the desired results.

The calcium sulfate (CaSO4) in the tube retains carbon dioxide selectively as it's heated, and thereby, removed from the solution.

In fact, gravimetric analysis was used to determine the atomic masses of many elements in the periodic table to six figure accuracy.

Gravimetric analysis, due to its high degree of accuracy, when performed correctly, can also be used to calibrate other instruments in lieu of reference standards.

Methods are often convoluted and a slight mis-step in a procedure can often mean disaster for the analysis (colloid formation in precipitation gravimetry, for example).

We can no longer use the thermodynamic equilibrium constant (i.e. in absence of diverse ions) and we have to consider the concentration equilibrium constant or use activities instead of concentration if we use Kth: We have calculated the solubility of AgCl in pure water to be 1.0 x 10−5 M, if we compare this value to that obtained in presence of diverse ions we see % increase in solubility = {(1.3 x 10−5 – 1.0 x 10−5) / 1.0 x 10−5} x 100 = 30% Therefore, once again we have an evidence for an increase in dissociation or a shift of equilibrium to right in presence of diverse ions.