Vol. 109 No. 3 (2013)

Resumen: La exigente demanda de nuevos materiales en nuestra sociedad y la preocupación por una química más verde, ha supuesto la revelación de una nueva generación de catalizadores altamente selectivos y sostenibles (catalizadores orgánicos) como herramienta útil para la síntesis de polímeros. Las ventajas que poseen estos catalizadores frente a los catalizadores organometálicos tradicionales en cuanto a toxicidad y versatilidad hacen de la organocatálisis y su aplicación en reacciones de polimerización un campo en continua expansión. Este trabajo aporta una visión actual de las posibilidades de la organocatálisis en los procesos de polimerización y nuestra opinión sobre los futuros retos de la organocatálisis en el siglo XXI.
Palabras clave: Organocatálisis, polímeros, química sostenible, ingeniería macromolecular.
Abstract: The demanding requirements of new materials in our society and concern for greener chemistry, has led to the revelation of a new generation of highly selective and sustainable catalysts (organic catalysts) as a useful tool for the synthesis of polymers. The advantages that these catalysts offer versus traditional organometallic catalysts in terms of toxicity and versatility makes the organocatalysis and their application in polymerization reactions a continuously expanding field. This work provides a current view of the possibilities of organocatalysis in polymerization processes and our opinion on the future challenges in the XXI century.
Keywords: Organocatalysis, polymers, sustainable chemistry, macromolecular engineering.

Resumen: La contaminación ambiental por hidrocarburos aromáticos policíclicos (HAP) es actualmente un problema muy extendido. Los HAP son generados por la combustión incompleta de combustibles fósiles entre otros y, además de sus propiedades tóxicas, son poco solubles en agua. Para abordar este problema, se utilizan surfactantes ya que favorecen la solubilidad de dichos compuestos hidrófobos. La temperatura también influye en las propiedades de los HAP y en el metabolismo de los microorganismos involucrados en su degradación. Enterobacter sp., Pseudomonas sp. y Stenothrophomonas sp., tienen una capacidad degradadora de naftaleno, fenantreno y antraceno eficiente a 15 y 25 ºC.
Palabras clave: Hidrocarburos aromáticos policíclicos, surfactantes, microorganismos.
Abstract: Environmental contamination by polycyclic aromatic hydrocarbons (PAH) is currently a widespread problem. PAHs are produced by incomplete combustion of fossil fuels and other materials. Moreover, PAHs are poorly soluble in water and they present toxic properties. In order to address this problem, surfactants are often used due to they favor the solubility of these hydrophobic compounds. Temperature influences both on the properties of PAHs and the metabolism of microorganisms involved in this process. Enterobacter sp., Pseudomonas sp. and Stenothrophomonas sp., have an efficient degrading capacity of naphthalene, phenanthrene and anthracene at 15 and 25 °C.
Keywords: Polycyclic aromatic hydrocarbons, surfactants, microorganisms.

Resumen: En julio de 1913 Niels Bohr publicaba el primero de una serie de artículos sobre un nuevo modelo de átomo basado en la hipótesis cuántica. No fue el primer modelo cuántico, como suele creerse, sino una síntesis de ideas dispersas y la introducción de una nueva hipótesis clave que daba sentido a todo: la existencia de distintos estados estacionarios para el electrón dentro del átomo.
Palabras clave: Modelo de Bohr, teoría cuántica, estados estacionarios, espectroscopía, historia.
Abstract: In July 1913 Niels Bohr published the first of a series of articles about a new model of the atom based on the quantum hypothesis. It was not the first quantum model, as it is usually believed, but a synthesis of separate ideas and the introduction of a key new hypothesis that made sense of them all: namely the existence of different stationary states for the electron within the atom.
Keywords: Bohr model, quantum theory, stationary states, spectroscopy, history.

A brief historical account on the theory proposed in 1922 by Wolfgang Ostwald and Ramón de Izaguirre for adsorption from solution is initiated with an examination of the circumstances under which that work was generated. After providing some biographic data of the authors prior to their formulation of the theory, a concise overview of the theory is presented. This is followed by an identification of further publications from both authors in the field of adsorption.

Keywords: History of chemistry, surface science, adsorption, JAE, Ostwald-de Izaguirre theory

This work completes the historical presentation of the theory proposed in 1922 by Wolfgang Ostwald and Ramón de Izaguirre for adsorption from solution. After examining biographic data for one of the authors following the formulation of the theory, the impact of the latter is examined either as a whole or through a classification of adsorption isotherms or an equation that describes adsorption of mixtures of miscible liquids by solids.

Keywords: History of Chemistry, surface science, adsorption, classification of isotherms, Ostwald-de Izaguirre equation

Resumen: El mol es, de las siete unidades fundamentales del Sistema Internacional, la que podríamos considerar genuinamente química. No obstante, es bastante común una comprensión errónea del concepto. Tiende a confundirse con la masa “un mol de ácido sulfúrico son 98 g de ácido sulfúrico” o con un número “un mol de agua son 6,022 · 1023 moléculas de agua”. Aun si comprendemos el verdadero significado de mol lo verdaderamente difícil puede ser intentar comunicárselo a nuestros estudiantes de ESO y bachillerato. ¿Cómo hacerlo? ¿Podemos esperar algún resultado de nuestro intento?
Palabras clave: Mol, Número de Avogadro, átomos y moléculas, enseñanza de la química, didáctica.
Abstract: The mole is one of the seven International System basic units, the one we could consider genuinely chemical. However, an erroneous understanding of this concept is quite common. It is usually mistaken with mass “a mole of sulphuric acid equals 98 g of sulphuric acid” or with a number “a mole of water equals 6,022 · 1023 molecules of water”. Even if we do understand the true meaning of mole it can be very difficult to try to put it across to our secondary school students. How can we do it? Can we expect any results from our attempts?
Keywords: Mole, Avogadro Number, atoms and molecules, teaching chemistry, didactics.

In this paper a group of undergraduate students of Chemistry tell how they have managed to identify and assign the spectral lines of a hydrogen-like atom coming from the spectrum of a faraway star.

Keywords: Chemistry students, hydrogen-like atoms, spectral lines, Rydberg formula, learning activities.

The noticeable decrease of the number of high school chemistry students suggests the need of developing strategies in order to achieve the levels of the past decade. In this work, some tools, applicable from the first educative levels to secondary and high school, are proposed. These strategies include the design of fun laboratory experiments for 6-7 year children, the creation of a peculiar team of researchers involved in the problems proposed to students, the availability of solved problems collections or taking part in external competitions, as the Chemistry Olympiad.

Keywords: Magic laboratory, Chemistry Olympiad, didactic of chemistry, solved problems