Moles and Number of Atoms

Converting between moles and number of atoms is similar to converting between dozens and number of nails. To convert between moles of atoms and number of atoms, we use the conversion factors  

For example, suppose we want to convert 3.5 mol of helium to a number of helium atoms. We set up the problem in the standard way. 

SOLUTION MAP We draw a solution map showing the conversion from moles of He to He atoms. 

EXAMPLE 6.1 Converting between Moles and Number of Atoms 

A silver ring contains 1.1 X 10 silver atoms. How many moles of silver are in the ring  

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The mass of mercury is given. Conversion from mass to number of moles and number of atoms... 

C02-0014. Although 10 mol is not very much mercury, the initial eraption blanketed the Yakima Valley with 35 metric tons of volcanic ash per acre. Given that a metric ton is 1000 kg, determine how much Hg the volcano deposited on every acre of the Yakima Valley, in grams, moles, and number of atoms. 

The notions of Avogadro s number and molar mass enable us to carry out conversions between mass and moles of atoms and between moles and number of atoms (Figure 3.2). We will employ the following conversion factors in the calculations ... 

We just learned how to convert between moles and number of atoms, which is like converting between dozens and number of nails. We need one more conversion factor to convert from the mass of a sample to the number of atoms in the sample. For nails, we used the weight of one dozen nails for atoms, we use the mass of one mole of atoms. 

To convert between moles and number of atoms, use Avogadro s number, 6.022 X 10 atoms = 1 mol, as a conversion factor. 

Relating Mass to the Number of Atoms The diagram shows the relationship between mass in grams, amount in moles, and number of atoms of an element in a sample. 

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. 

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