Search results for "Avogadro constant"
showing 3 items of 3 documents
Enseñanza de las ciencias : revista de investigación y experiencias didácticas
2003
Se discuten algunas de las conclusiones de varios trabajos históricos recientes sobre Amedeo Avogadro y la teoría atómica del siglo XIX. A través de pequeños extractos de publicaciones famosas de Avogadro, se analizan las características principales de sus aportaciones a la teoría atómica del siglo XIX. También se analizan los principales métodos de cálculo de pesos atómicos de esos años y se discute el papel de las ideas de Avogadro en este tema. Estas conclusiones se contrastan con la imagen que actualmente los libros de texto dan acerca de este autor. Finalmente, esta última comparación conduce a una discusión sobre el papel de la historia de la ciencia en los libros de texto. This paper…
Mass and Gravity
2014
The book starts with a survey on the development of the concept ‘mass’ and of theories of gravity, beginning with Greek’s ideas on mass, Galileo’s experiments, Newton’s laws and their extension by Einstein’s theory of relativity. Data from measurements of the gravitational force on Sun, planets and the Moon are presented. Kepler’s laws on moving masses in the gravitational field are discussed as well as new discoveries on the expansion of the universe. Fundamental interactions of particles and particle/wave duality are described. The Theory of Everything is mentioned. The definition of the international unit of mass is reported as well as alternatives like watt or voltage balance, counting …
1984
Sedimentation coefficients of S of polystyrene covering a broad range of molecular weights M, are measured in toluene and 2-butanone in the semidilute regime. The results are compared with literature data using a plot of S · NA · η/(1 − νρ) = M · η/f versus concentration c, allowing experiments in different solvents of different density ρ and viscosity η to be compared (ν: partial specific volume of polymer; f: friction coefficient; NA: Avogadro number). According to scaling theory for concentrations higher than a critical concentration c, linear plots are to be expected. This is true for the theta-solvent cyclohexane, but for the theta-solvent cyclopentane as well as for the thermodynamica…