Conversion factor Avogadro constant

Table 47. Constants and Conversion Factors Avogadro s number = 6.023 X 10s per mole Electronic charge = 4.802 X 10-10 e.s.u.

Note that calculated energies are the first ionization energies per one atom because we used only one photon. To calculate the first ionization energies in eV as asked in the exercise, the above energies must be multiplied by the Avogadro s constant (to obtain the energies in J mof ) and then divided by the conversion factor 96485 J moT eV to obtain the values in eV ... 

Ultimately we need to complete the conversion mL milk atoms There is no single conversion factor that allows us to complete this conversion in one step, so we anticipate having to complete several steps or conversions. We are told the milk contains 1.65 mg K/mL = 1.65 X 10 g K/mL, and this information can be used to carry out the conversion mL milk g K. We can carry out the conversions g K mol K atoms K by using conversion factors based on the molar mass of K and the Avogadro constant. The final conversion, atoms K atoms K, can be carried out by using a conversion factor based on the percent isotopic abundance of K. A complete conversion pathway is shown below ... 

Molar mass and the Avogadro constant are used in a variety of calculations involving the mass, amount (in moles), and number of atoms in a sample of an element. Other conversion factors may also be involved in these calculations. The mole concept is encountered in ever broader contexts throughout the text. 

TABLE 3.1 Density, Molar Mass, and the Avogadro Constant as Conversion Factors ... 

The central focus is again the conversion of a measured quantity to an amount in moles. Because the density is given in g/mL, it will be helpful to convert the measured volume to milliliters. Then, density can be used as a conversion factor to obtain the mass in grams, and the molar mass can then be used to convert mass to amount in moles. Finally, the Avogadro constant can be used to convert the amount in moles to the number of molecules. In summary, the conversion pathway is /xL L g — mol molecules. 

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