0000000000166747
AUTHOR
Roberto Zingales
la semicella Zn(Hg)/Zn++ ed alcune sue applicazioni analitiche
Storte, ampolle e gas. Breve storia per un Museo di Chimica.
Unusual oxidation states of cations in aqueous solutions
Raffaele Piria e Stanislao Cannizzaro, dal 1848 al 1860 e oltre: due chimici meridionali nell'Italia Risorgimentale e post-unitaria
Come altri scienziati italiani a metà ottocento, Raffaele Piria e Stanislao Cannizzaro, con la loro attività scientifica e politica, hanno dato un notevole contributo, non solo al progresso della Chimica, ma anche alla costituzione del Regno d’Italia. La loro continua e lungimirante attività, sia sui campi di battaglia che nelle aule universitarie o parlamentari, ha contribuito alla rinascita culturale, sociale ed economica del Paese. Questo articolo, completato a conclusione dell’Anno Internazionale della Chimica, e delle celebrazioni per il 150° anniversario della fondazione dello stato italiano, vuole ricordare la loro attività politica e scientifica, sia in ambito locale, che nazionale,…
La ricerca dei componenti ultimi della materia:l'approccio filosofico, quello chimico e quello fisico
The complex formation equilibria between Cd(II), Pb(II) and iminodiacetic acid in NaClO4 0.93 Mw at 25°C
The Formal Redox Potential of the Ti(IV, III) Couple at 25 °C in 1 M HCl 2 M NaCl Medium
The formal redox potential of the Ti(IV, III) couple has been determined at 25 degrees C in 1 M HCl, 2 M NaCl aqueous medium, by emf measurements of a junction-free cell with glass and mercury electrodes. Ti(III) and Ti(IV) concentrations were changed by controlled electrolysis. The mean value of the searched formal potential, in a large range of total titanium concentration, is 9 +/- 1 mV against the molar hydrogen electrode in the same ionic medium.
Le proprietà acide dello ione uranile in soluzione acquosa LiClO4 3,6 molale a 75 e 100°C
Stanislao Cannizzaro patriota, insegnante, statista
The Formal Potential of the Ti(IV-III) Couple at 25°C in the TiCl4, TiCl3, HCl, NaCl Mixtures at 3 M tital Cl-.
The acidic properties of the uranyl ion in LiClO4 aqueous solutions 3.6 molal at 75 and 100°C
Il completamento della Tabella Periodica
Cannizzaro e la Scuola Chimica di Palermo (1862-1871)
Complex Formation of the Uranyl (UO22+) Ion with the Diethylene Triaminopentaacetate (DTPA) Ligand at 25 °C in 3 M Sodium Perchlorate
The complex formation between the uranyl (UO22+) ion and the diethylene triaminopentaacetate ligand (DTPA) has been investigated at 25 °C, in a 3 M sodium perchlorate medium. The overall protonation constants βjH of the free ligand have been previously determined in this ionic medium: six protonated species (HjA), with j ranging from 1 to 6, together with the free anion A5− have been identified in the concentration range from (3·10−3 to 13·10−3) mol·kg−1. Four complex species, H2UO2A−, HUO2A2−, UO2A3−, and UO2AOH4−, have been identified in the total uranyl concentration range from (1.1·10−3 to 5.7·10−3) mol·kg−1, and their overall stability constants determined, keeping the metal to ligand …
Stanislao Cannizzaro and the Development of Chemistry in Palermo from 1862 to 1871
Stanislao Cannizzaro worked at Palermo University for about ten years. There he managed to establish a modern and well-equipped chemical laboratory. His international fame attracted co-workers even from abroad: Naquet, Lieben, and Körner came to Palermo to work with him. This greatly improved the quality of teaching and of research in Palermo, which became a worldwide acknowledged center of chemical culture. In Palermo, atomic-molecular theory was extensively taught and research was carried out on chemical atomicity (valence) and spatial structures of both aliphatic and aromatic organic molecules: Körner found the relative positions of substituent groups on the benzene ring, Paternò proved …
The formal redox potential of the Yb(III,II) Couple at 0°C in 3.22 molal NaCl medium
Following our previous investigations on aqueous solutions of hypooxidized and iperoxidized species, we managed, by lowering the temperature of the solutions to 0 degrees C, to obtain, by electrochemical methods, Yb(II) and Yb(III) mixtures, enough stable to determine by a potentiometric method the formal redox potential of the Yb(IlI, II) couple. Its value, in a large range of total Ytterbium concentration, is -1233 +/- 3 mV against the molal hydrogen electrode in the 3.22 m NaCl medium.
Multidisciplinary learning at the University scientific museums: the Bunsen burner
We report on a laboratory activity carried out together with secondary school (high-school) students, with the aim of increasing their interest toward historical scientific instruments and stimulate their approach to scientific knowledge. To this purpose, we propose a hands-on activity that can be fruitfully performed at the University scientific museums. We organized a one-week summer stage at the Historical Collection of Physics Instruments and at the Museum of Chemistry of the University of Palermo. A group of selected students attended it, under the tutoring of university researchers. They were showed some Bunsen burners belonging to the collections, how they are restored, how they work…
Nascita ed evoluzione del linguaggio chimico
Il linguaggio chimico è nato e si è sviluppato come linguaggio simbolico, in paral-lelo con quello esteso. Il primitivo simbolismo chimico si basava su significati magici e criptici, per poi evolvere fino ad assumere il valore di linguaggio compatto, molto simile a quello algebrico. Sebbene convenzionale, il linguaggio chimico può essere considerato naturale, perché, nei suoi termini e nei suoi simboli, esso cerca di dar conto della natura e delle proprietà degli oggetti. Per questo, la storia della sua origine e del suo sviluppo può essere presa a modello dello sviluppo degli altri linguaggi delle scienze naturali.
The possible use of the half cell Zn(Hg)/Zn2+ in ionic equilibria studies
Dioxouranium(VI) hydrolysis at 75 and 100°C in 3.6 molkg-1 LiClO4
This work concerns the acidic properties of uranyl ion UO22+ at 75 and 100 °C in 3.6 molal (molkg-1 solvent) LiClO4 aqueous medium. The investigation was carried out by a coulometric-potentiometric technique. Direct and reverse acid base titrations were carried out in order to check the achievement of actual equilibrium conditions. Moreover, in order to reveal oversaturation conditions, a further check was carried out on clean saturated hydrolyzed solutions.
Agostino Oglialoro Todaro, allievo di Paternò e mentore di Marussia Bakunin
L'attività di ricercatore e di docente di Agostino Oglialoro Todaro è discussa e messa in relazione con il contesto storico nella Napoli di fine ottocento e inizio novecento.
Batch experiments for the determination of the Ti(IV,III) couple in 1 moldm-3 HCl, 2 moldm-3 NaCl medium at 25°C
The determination of the Ti(IV, III) redox couple formal potential in 1 M HCl 2 M NaCl medium at 25°C through batch experiments involving the preparation of Ti(IV) and Ti(III) mixtures via the reaction of Ti(IV) with Zinc amalgam, has been carried out with emf measurements in order to verify the correctness of the previous value that the authors obtained by a coulometric-potentiometric investigation in the same conditions. The results from the two independent methods are in good agreement: 9 ± 1 mV the first and 9 ± 2 the average batch result.
Stanislao Cannizzaro: vita e opere nel contesto palermitano
E' descritta l'attività politica, scientifica e didattica di Stanislao Cannizzaro a Palermo, nel decennio 1862-1871, in particolare nei riguardi delle fondazione e dello sviluppo dell'Istituto Tecnico. Tra gli altri risultati, l'aver incoraggiato e agevolato la crescita scientifica di due giovani talenti, il tedesco Guglielmo Koerner e il palermitano Emanuele Paternò, che diedero un contributo fondamentale allo sviluppo della chimica organica ottocentesca.
Il potenziale redox della coppia Ti(IV,III) a 25°C nel mezzo HCl 1 M NaCl 2 M
L’introduzione dei laboratori didattici nell’insegnamento universitario della Chimica in Europa e in Italia Il contributo di Stanislao Cannizzaro e dei suoi allievi
Tra la fine del settecento e la prima metà si completò quel profondo processo che trasformò la Chimica da arte pratica al servizio di discipline più nobili, come la medicina, la farmacia, la metallurgia, in una scienza vera e propria, pienamente autonoma e saldamente fondata su basi numeriche. Questa trasformazione fu, in larga parte, il risultato dell’accurata e rigorosa attività sperimentale di molti scienziati di diversi paesi, che fornirono un fondamento teorico all’approccio fenomenologico che caratterizzava la disciplina. L’introduzione di corsi di laboratorio per studenti fu uno dei punti qualificanti della grande riforma della didattica e dell’organizzazione dei corsi che ebbe luogo…
From Masurium to Trinacrium: The Troubled Story of Element 43
The first man-made chemical element was that with atomic number 43. It was produced at the University of Californiaâ€sA„A¬Berkeley (by neutron bombardment of a molybdenum plate and was chemically identified at the University of Palermo (Italy) in 1937 by Segre and Perrier. Previous attempts to identify it in natural ore had been unsuccessful, owing to the short life of its isotopes. Notwithstanding, several claims of its discovery had appeared in the chemical literature. The history of this discovery clearly shows the dramatic improvements of chemical analytical techniques and criteria in the first half of 20th century. In 1949 its discoverers proposed to call it technetium, which means pro…
Stanislao Cannizzaro nel centenario della scomparsa
The determination of mineral acidity excess in solutions containing Ga(III), Al(III), Bi(III)
Abstract A new procedure is proposed to carry out volumetric determinations of the strong acid content of a solution in the presence of inorganic cations such as Ga 3+ , Al 3+ , Bi 3+ which, showing in aqueous solution an acidic behaviour, introduce non negligible interferences in these determinations. Before the acid–base titration, an equivalent amount of a ligand, such as dihydrogen ethylendiamino tetraacetate is added, in order to strongly complex the cation masking it toward the successive addition of a strong base. Interferences are thus removed, and the volumetric determination of the strong acid excess plus the hydrogen ions set free from the ligand, as a consequence of the complex …
Stanislao Cannizzaro, insegnante
The formal redox potential of the U(IV-III) couple at 25°C in the aqueous 3 M (Na+, H+) Cl- medium
The complex formation equilibria between Zn(II) and iminodiacetic acid (IDA) in NaClO4 1 M at 25°C
Chemists and Physicists searching for element 43
An approach to the Venturi effect by historical instruments
Student understanding of the laws that describe the flow of a fluid is often hampered by a defective knowledge of basic classical mechanics (kinematics, statics, dynamics, and conservation laws) and by wrong common-sense ideas about quantities related to fluids, such as velocity and pressure. A pedagogical discussion about the Venturi effect, based on experiments inspired by historical instruments, may be an effective way to introduce students to these laws. In this paper, we discuss an approach to the understanding of the Venturi effect based on the study of historical instruments and on simple experiments. In particular, after a presentation of the Venturi effect, also from a historical p…
1937, Palermo: la scoperta del tecneto
The Italian and international scenario of Physics and Chemistry in the thirties will be described, in order to introduce and better understand the successive steps that followed to the discovery of element 43 (Technetium). Of course, more emphasis will be given to the academic life in Palermo, where the discover took place: main characters and bit actors will be treated to give a full picture of the milieu. Finally, a glance will be given to the political events preceding and following the discover, and their consequences on people involved, as the possibility to realize in Palermo a multi disciplinary research team of high level, working on innovative arguments, was deeply compromised by t…