### Note the Pattern

The molar massive of any kind of substance is its atomic mass, molecular mass, or formula fixed in grams every mole.

You are watching: Calculate the mass percent of chlorine in ccl3 f (freon-11).

The regular table lists the atom mass of carbon as 12.011 amu; the typical molar massive of carbon—the massive of 6.022 × 1023 carbon atoms—is thus 12.011 g/mol:

problem (formula) Atomic, Molecular, or Formula massive (amu) Molar fixed (g/mol)
carbon (C) 12.011 (atomic mass) 12.011
ethanol (C2H5OH) 46.069 (molecular mass) 46.069
calcium phosphate 310.177 (formula mass) 310.177

The molar fixed of naturally developing carbon is various from that of carbon-12 and also is not an integer due to the fact that carbon occurs together a mixture of carbon-12, carbon-13, and also carbon-14. One mole of carbon still has 6.022 × 1023 carbon atoms, but 98.89% that those atoms room carbon-12, 1.11% space carbon-13, and a trace (about 1 atom in 1012) room carbon-14. (For more information, see section 1.6 ) Similarly, the molar fixed of uranium is 238.03 g/mol, and the molar massive of iodine is 126.90 g/mol. As soon as we deal with elements such together iodine and sulfur, which take place as a diatomic molecule (I2) and also a polyatomic molecule (S8), respectively, molar fixed usually describes the mass of 1 mol that atoms of the element—in this situation I and S, not come the mass of 1 mol of molecules that the element (I2 and also S8).

The molar mass of ethanol is the mass of ethanol (C2H5OH) that contains 6.022 × 1023 ethanol molecules. Together you calculation in example 1, the molecular mass the ethanol is 46.069 amu. Since 1 mol the ethanol contains 2 mol the carbon atoms (2 × 12.011 g), 6 mol the hydrogen atoms (6 × 1.0079 g), and also 1 mol that oxygen atoms (1 × 15.9994 g), its molar massive is 46.069 g/mol. Similarly, the formula massive of calcium phosphate is 310.177 amu, so its molar mass is 310.177 g/mol. This is the mass of calcium phosphate that consists of 6.022 × 1023 formula units.

The mole is the basis of quantitative dearteassociazione.orgistry. It provides dearteassociazione.orgists with a method to convert easily between the fixed of a substance and also the variety of individual atoms, molecules, or formula devices of the substance. Vice versa, it permits dearteassociazione.orgists to calculation the fixed of a substance essential to achieve a desired variety of atoms, molecules, or formula units. Because that example, to convert moles that a problem to mass, we use the relationship

$$(moles)(molar \; mass) \rightarrow mass \tag1.71$$

or, an ext specifically,

$$moles\left ( \dfracgramsmole \right ) = grams$$​

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The mass of 1.75 mol the S2Cl2 is calculated together follows:

$$moles\; S_2Cl_2 \left = mass\; S_2Cl_2$$

$$1.75\; mol\; S_2Cl_2\left ( \dfrac135.036\; g\; S_2Cl_21\;mol\;S_2Cl_2 \right )=236\;g\; S_2Cl_2$$

B The formula fixed of Ca(ClO)2 is obtained as follows:

 1Ca (1 atom )(40.078 amu/atom) = 40.078 amu 2Cl (2 atoms)(35.453 amu/atom) = 70.906 amu 2O (2 atoms)(15.9994 amu/atom) = 31.9988 amu Ca(ClO)2 formula fixed of Ca(ClO)2 = 142.983 amu

The molar fixed of Ca(ClO)2 is 142.983 g/mol

$$moles\; Ca\left ( ClO \right )_2\left < \dfracmolar\; mass\; Ca\left ( ClO \right )_21\; mol\; Ca\left ( ClO \right )_2 \right >=mass\; Ca\left ( ClO \right )_2$$

$$1.75\; mol\; Ca\left ( ClO \right )_2\left < \dfrac142.983\; g Ca\left ( ClO \right )_21\; mol\; Ca\left ( ClO \right )_2 \right >=250.\; g\; Ca\left ( ClO \right )_2$$​

Exercise

Calculate the fixed of 0.0122 mol of each compound.

Si3N4 (silicon nitride), used as bearings and rollers (CH3)3N (trimethylamine), a corrosion inhibitor