Concentrations of impurities in fluids often follow Zipf's law, that is, relatively few impurities occur at high concentrations and numerous impurities occur at low concentrations. The concentrations of compounds in air and of elements in ocean water are examples of such distributions. This principle can be used to predict the number of components in a mixture, which occur above certain concentration level, also beyond the range of analytical methods. In most practical applications the existence of minor components can be ignored, but the level of concentration, at which certain component can be ignored depends on the specific problem.
The volumes of reactions in solution are usually ignored in problem solving. Neglection of reaction volumes may lead to errors on the order of 1 % in the final result. Calculation of the volume of neutralization reaction based on the specific densities of solutions from chemical tables is demonstrated.
K. Marczewska-Boczkowska, M. Kosmulski and J. Olchowik
Electrochemical study of corrosion of copper in 1-alkyl-3-methylimidazolium tetrafluoroborates
Copper is resistive to corrosion in dry and chloride-free 1-alkyl-3-methylimidazolium tetrafluoroborates at room temperature, and the corrosion rate decreases with the chain length of the substituent in imidazolium ring and increases with the temperature. The activation energies of corrosion are on the order of 50 kJ/mole. The corrosion in enhanced in the presence of traces of chlorides.