### Note the Pattern

The molar fixed of any type of substance is its atom mass, molecular mass, or formula mass in grams per mole.

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The regular table list the atomic mass that carbon together 12.011 amu; the average molar mass of carbon—the fixed of 6.022 × 1023 carbon atoms—is therefore 12.011 g/mol:

problem (formula) Atomic, Molecular, or Formula mass (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 different from the of carbon-12 and is no an integer since carbon occurs as a mixture the carbon-12, carbon-13, and carbon-14. One mole of carbon still has actually 6.022 × 1023 carbon atoms, but 98.89% that those atoms room carbon-12, 1.11% room carbon-13, and a map (about 1 atom in 1012) space carbon-14. (For more information, see section 1.6 ) Similarly, the molar mass of uranium is 238.03 g/mol, and the molar massive of iodine is 126.90 g/mol. As soon as we attend to elements such together iodine and also sulfur, which happen as a diatomic molecule (I2) and also a polyatomic molecule (S8), respectively, molar massive usually refers to the fixed of 1 mol the atoms the the element—in this situation I and also S, not come the fixed of 1 mol that molecules of the facet (I2 and S8).

The molar mass of ethanol is the fixed of ethanol (C2H5OH) that includes 6.022 × 1023 ethanol molecules. As you calculated in example 1, the molecule mass the ethanol is 46.069 amu. Since 1 mol the ethanol includes 2 mol the carbon atoms (2 × 12.011 g), 6 mol that hydrogen atom (6 × 1.0079 g), and 1 mol that oxygen atoms (1 × 15.9994 g), that molar massive is 46.069 g/mol. Similarly, the formula mass of calcium phosphate is 310.177 amu, for this reason its molar massive is 310.177 g/mol. This is the fixed of calcium phosphate that includes 6.022 × 1023 formula units.

The mole is the communication of quantitative historicsweetsballroom.comistry. It gives historicsweetsballroom.comists v a way to transform easily between the mass of a substance and the variety of individual atoms, molecules, or formula devices of that substance. Conversely, it allows historicsweetsballroom.comists to calculate the fixed of a substance needed to acquire a desired number of atoms, molecules, or formula units. For example, to convert moles the a substance to mass, we usage the relationship

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

or, much more specifically,

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

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The fixed of 1.75 mol that S2Cl2 is calculated as 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 massive of Ca(ClO)2 is derived 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 massive 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 massive of 0.0122 mol of each compound.

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