### Note the Pattern

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

You are watching: Calculate the formula weight of ethanol, c2h5oh

The regular table lists the atomic mass of carbon as 12.011 amu; the average molar mass of carbon—the massive of 6.022 × 1023 carbon atoms—is because of this 12.011 g/mol:

problem (formula) Atomic, Molecular, or Formula fixed (amu) Molar massive (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 arising carbon is various from that of carbon-12 and is no an integer due to the fact that carbon occurs as a mixture the carbon-12, carbon-13, and also carbon-14. One mole of carbon still has actually 6.022 × 1023 carbon atoms, however 98.89% of those atoms space carbon-12, 1.11% space carbon-13, and a map (about 1 atom in 1012) space carbon-14. (For much more information, see ar 1.6 ) Similarly, the molar mass of uranium is 238.03 g/mol, and the molar fixed of iodine is 126.90 g/mol. When we address elements such together iodine and also sulfur, which occur as a diatomic molecule (I2) and a polyatomic molecule (S8), respectively, molar fixed usually refers to the massive of 1 mol of atoms the the element—in this case I and S, not to the fixed of 1 mol that molecules that the facet (I2 and S8).

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

The mole is the basis of quantitative invernessgangshow.netistry. It gives invernessgangshow.netists through a way to convert easily in between the fixed of a substance and also the variety of individual atoms, molecules, or formula devices of that substance. Conversely, it permits invernessgangshow.netists to calculation the fixed of a substance essential to obtain a desired variety of atoms, molecules, or formula units. Because that example, to convert moles that a substance to mass, we use the relationship

( (moles)(molar ; mass) ightarrow fixed ag1.71 )

or, more specifically,

( molesleft ( dfracgramsmole ight ) = grams )​

How Many Pounds Is 58 Kg ) Converts To 127, 58 Kg To Lbs

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_2left ( dfrac135.036; g; S_2Cl_21;mol;S_2Cl_2 ight )=236;g; S_2Cl_2 )

B The formula mass 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 fixed of Ca(ClO)2 = 142.983 amu

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

( moles; Caleft ( ClO ight )_2left < dfracmolar; mass; Caleft ( ClO ight )_21; mol; Caleft ( ClO ight )_2 ight >=mass; Caleft ( ClO ight )_2 )

( 1.75; mol; Caleft ( ClO ight )_2left < dfrac142.983; g Caleft ( ClO ight )_21; mol; Caleft ( ClO ight )_2 ight >=250.; g; Caleft ( ClO ight )_2 )​

Exercise

Calculate the mass of 0.0122 mol of each compound.

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