Avogadro, life

How can we count such a large number of items as Avogadro s number One way, which we also can use in everyday life, is to weigh a small number and the entire quantity. We can count the small number, and the ratio of the number of the small portion to the number of the entire quantity is equal to the ratio of their masses. 

Departmenf of Environmenfal and Life Sciences, University of Easfern Piedmont Amedeo Avogadro , Spalto Marengo, 33, 1-15100, Alessandria, Italy... 

Chiefly remembered for his reinstatement of Avogadro s hypothesis and his subsequent reform of atomic weights was the Italian chemist Stanislao Cannizzaro. His life and (especially) his work have been commemorated in a book by John Bradley, appearing in German86 and English87 editions. There have also been three volumes of Cannizzaro correspondence, edited by L. Paoloni88 90... 

Research the life of the Italian chemist Amedeo Avogadro (1776-1856) and how his work led scientists to the number of particles in a mole. 

Atoms and molecules are incredibly small. Just as the dozen is used as a convenient number of items in everyday life, chemists use the mole to describe quantities of atoms or molecules. One mole is 6.02 x 10 items, a number called Avogadro s number. Using moles simplifies calculations. The number of formula units can be converted to moles of the same substance, and vice versa, using Avogadro s number. Some authors refer to a mole as a gram molecular mass because one mole of molecules has a mass in grams equal to its molecular mass. Mole is abbreviated mol. 

From the definition of curie, calculate Avogadro s number. Given that the molar mass of Ra-226 is 226.03 g/mol and that it decays with a half life of... 

Amedeo Avagadro was born in 1776 in Turin, a city in northwestern Italy. Avogadro spent his entire life within 80 kilometers (50 miles) of Turin, for from the cultural centers where chemistry was becoming a science. He received a classical education in the humanities, earned a doctorate in law in... 

The conversion from activity to mass or molar units is dependent on the half-life of the isotope in question. Activity (A) is the product of the number of atoms of the isotope present (N) and its decay constant (1) A = IN. The decay constant, 1, is related to the half-life by txjx = (/ 2)/7. Using this equation, it is simple to convert from Bq to mol, given the decay constants in units of s, and Avogadro s number of 6.023 X 10 atoms moU. ... 

The disintegration rate can be determined from the measured values of radionuclide mass m in grams and the half-life ti/2 in seconds. Equation (2.7) relates the decay rate to the mass in terms of Avogadro s number Ay of 6.02 x 10 atoms per mol and the isotope mass number A in g/mol ... 

In everyday life we use such familiar counting units as dozen (12 objects) and gross (144 objects). In chemistry the counting unit for numbers of atoms, ions, or molecules in a laboratory-size sample is the mole, abbreviated mol. One mole is the amount of matter that contains as many objects (atoms, molecules, or diatever other objects we are considering) as the number of atoms in exactly 12 g of isotopicaUy pure C. From experiments, scientists have determined this number to be 6.0221421 X 10, diich we will usually round to 6.02 X 10. Scientists call this value Avogadro s number, N, in honor... 

Specific activity The amount of radioactivity per unit mass (i.e., Bq/mol). This can be calculated as follows (In 2) (Avogadro s number)/(half-life in seconds). 

The specific activity oq of a radionuclide is the number of disintegrations per second per unit mass, expressed in Bq/kg it depends only on the half-life t and the relative atomic weight A, the decay constant X is related to the half-life by X X t = In 2, and the number of atoms N per kg is determined from the atomic weight by Avogadro s number Nf, ... 

Jean-Baptiste Perrin (1870-1942). .. was a French physicist who worked on various subjects, for instance, on cathode rays, fluorescence, sound propagation, and the decay of radium. A major part of his scientiflc life was dedicated to colloids. His investigations on the Brownian motion of colloids by means of the previously developed ultramicroscope verified Einstein s statistic explanation of this phenomenon and thereby confirmed the atomic nature of matter. Moreover, Perrin was able to closely limit the possible range of Avogadro s number and he discovered the sedimentation-diffusion equilibrium. For his work on the discontinuous structure of matter and especially for his discovery of sedimentation equilibrium he received 1926 the Nobel Prize in Physics. 

Tyj half-life of the radionuclide X in s Nj Avogadro s constant 6.02204532 x 10 mol dimensionless atomic isotopic abundance dimensionless mass fraction of the radionuclide in the material m mass of material in kg... 

---