Avogadro determination

Avogadro determined that water is composed of particies. 

Avogadro s number, L The number of particles (atoms or molecules) in one mole of any pure substance. L = 6 023 x 10. It has been determined by many methods including measurements of Brownian movement, electronic charge and the counting of a-particles. 

Having detemiined A b and knowing that the gas constant R = 8.314JK from macroscopic measurements on gases, determine Avogadro s number L from the relationship... 

An important historic application of this relationship was the determination of Avogadro s number from measurements of light scattered by the atmosphere (see Problem 3). 

Prepare a log-log plot of rx versus X and evaluate the slope as a test of the Rayleigh theory applied to air. The factor M/pN in Eq. (10.36) becomes 6.55 X 10 /No, where Nq is the number of gas molecules per cubic centimeter at STP and the numerical factor is the thickness of the atmosphere corrected to STP conditions. Use a selection of the above data to determine several estimates of Nq, and from the average, calculate Avogadro s number. The average value of n - 1 is 2.97 X 10" over the range of wavelengths which are most useful for the evaluation of N. ... 

Knowing Avogadro s number and the atomic mass of an element, it is possible to calculate the mass of an individual atom (Example 3.2a). You can also determine the number of atoms in a weighed sample of any element (Example 3.2b). 

Stanislao Cannizzaro, professor of chemistry at f the University of Genoa. At a conference held in I Karlsruhe in 1860, he persuaded the chemistry community of the validity of Avogadro s law and showed how it could be used to determine molar and atomic masses, i The quantity now called "Avogadro s number (6.02 x 10 /mol) was first estimated in = 1865, nine years after Avogadro died. Not until... 

Regularities observed in the behavior of gases have contributed much to our understanding of the structure of matter. One of the most important regularities is Avogadro s Hypothesis Equal volumes of gases contain equal numbers of particles (at the same pressure and temperature). This relationship is valuable in the determination of molecular formulas—these formulas must be known before we can understand chemical bonding. 

This returns us to the problem of the determination of molecular weight. Avogadro s Hypothesis provides one of the convenient ways of measuring molecular weight if the substance can be vaporized. 

The molar masses of elements are determined by using mass spectrometry to measure the masses of the individual isotopes and their abundances. The mass per mole of atoms is the mass of an individual atom multiplied by Avogadro s constant (the number of atoms per mole) ... 

Avogadro s number is the conversion factor that iinks the number of moles with the number of individual particles. To determine the number of atoms in a sample of an element, we multiply the number of moles by Avogadro s number — n Likewise, if a sample contains a certain number of atoms, the number of moles in the sample... 

The relationship N = F/e provides an excellent method of calculating an accurate value of Avogadro s number from the values of Faraday and the experimentally determined electronic charge, e. 

If no side reactions occur at the electrode that would participate in the overall current flow, then the Faraday law can be used not only to measure the charge passed (i.e. in coulometres see Section 5.5.4) but also to define the units of electric current and even to determine Avogadro s constant. 

If Type I adsorption behavior is obeyed, a plot of PA/v versus PA should be linear with slope l/vm. Once the volume corresponding to a mono-layer has been determined, it can be converted to the number of molecules adsorbed by dividing by the molal volume at the reference conditions and multiplying by Avogadro s number (N0). When this number of molecules is multiplied in turn by the area covered per adsorbed molecule (a), the total surface area of the catalyst (S) is obtained. Thus,... 

Now we can determine the mass per A1 atom, and a value for the Avogadro constant. 

The number of elementary entities in 1 mol is an experimentally determined quantity, and is called the Avogadro constant L, which has the value 6.022 x 1023 mol-1. The Avogadro constant is also (incorrectly) called the Avogadro number . It is... 

Avogadro, A. 1811. Essay on a Manner of Determining the Relative Masses of the Elementary Molecules of Bodies, and the Proportions in Which They Enter into These Compounds. J. Physi. 73, 58-76. [Alembic Club Reprint No. 4] Translated paper available online at http // webserver.lemoyne.edu/faculty/giunta/avogadro.htinl. 

Avogadro, A. (1811). D une maniere de determiner les masses relatives de molecules elementaires des corps, et les proportions selon lesquelles elles entrent dans ces combinaisons. Journal de Physique LXXIII 58-76. 

The mole is the most important concept in this chapter. Nearly every problem associated with this material requires moles in at least one of the steps. You should get into the habit of automatically looking for moles. There are several ways of finding the moles of a substance. You may determine the moles of a substance from a balanced chemical equation. You may determine moles from the mass and molecular weight of a substance. You may determine moles from the number of particles and Avogadro s number. You may find moles from the moles of another substance and a mole ratio. Later in this book, you will find even more ways to determine moles. In some cases, you will be finished when you find moles, in other cases, finding moles is only one of the steps in a longer problem. 

The most important concept when working stoichiometry problems such as this one is moles. We must have moles to proceed. The mole determination of iodine will involve the molar mass of iodine (2 x 126.9 g/mol), while the mole determination of fluorine will involve Avogadro s number (since we have number of fluorine molecules). We can find the moles of each as follows ... 

In this chapter, you learned how to balance simple chemical equations by inspection. Then you examined the mass/mole/particle relationships. A mole has 6.022 x 1023 particles (Avogadro s number) and the mass of a substance expressed in grams. We can interpret the coefficients in the balanced chemical equation as a mole relationship as well as a particle one. Using these relationships, we can determine how much reactant is needed and how much product can be formed—the stoichiometry of the reaction. The limiting reactant is the one that is consumed completely it determines the amount of product formed. The percent yield gives an indication of the efficiency of the reaction. Mass data allows us to determine the percentage of each element in a compound and the empirical and molecular formulas. 

The values of P, T, and n may be used to determine the volume of a gas. If this volume is to be used with Avogadro s law of 22.4 L/mol, the combined gas law must be employed to adjust the volume to STE This equation will use the measured values for P and Talong with the calculated value of V. These values are combined with STE conditions (0°C (273.15 K) and 1.00 atm) to determine the molar volume of a gas. 

Born equation Jphys chemJ An equation for determining the free energy of solvation of an ion in terms of the Avogadro number, the ionic valency, the ion s electronic charge, the dielectric constant of the electrolytic, and the ionic radius. born i kwa zhan J... 

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