Mario E. Cardinali

GASEOUS EQUILIBRIA: SOME OVERLOOKED ASPECTS

For some gaseous equilibria, with particular stoichiometric characteristics, the addition of some reactant or products, as large as it may be, when operated under constant temperature and pressure, cannot cause a (practically) complete shift of the equilibrium to the right, or to the left. The effect of the addition is counteracted by the increase of volume that the system undergoes to keep constant the pressure. [Chem. Educ. Res. Pract. Eur.: 2000, 1, 145-149]

An always‐converging, successive‐substitution, fast algorithm to perform chemical equilibrium calculations

The equation to find the equilibrium value ξe of the degree of advancement for a chemical reaction is rearranged to the form of a successive‐substitution algorithm, which, over the previously described algorithms of the same kind, has the advantage of being always convergent to ξe and, usually, at very fast rate. How to perform the rearrangement is explained in detail, and the proof of the convergence of the algorithm thus obtained is given. A numerical example to test the performance of the algorithm is presented.

pH of simple ampholytes and related compounds. A general, always‐converging, iterative algorithm

For the aqueous solutions of those electrolytes whose acid‐base behaviour is completely described by only one acid andonly one basic ionization process, a new, original, iterative algorithm for the calculation of their pH values is derived from the exact, electroneutrality equations, in a unitary fashion, although these electrolytes belong to different classes. The fact that this algorithm always converges to the root of these equations is given a qualitative proof.

Hydrolysis of salts

From a series of letters dealing with a paper from an earlier issue in this Journal (November 1987, page 957).

Two further simple methods for calculating the critical compressibility factor for the Redlich-Kwong equation of state

The authors believe that the method suggested here can profitably replace, at a didactic level, the conventional approach, which involves the first and second derivatives of the equation of state for a real gas.

Boiling Temperature vs. Composition. An Almost-Exact Explicit Equation for a Binary Mixture Following Raoult's Law.

A simple method that leads directly to the boiling temperature of a binary mixture as a function of its composition.