Molar masses can range from 18 grams/mole to hundreds of grams/mole.

What is Molar Mass?

**Molar Mass By Gabriela Rodriguez-Castillo,Andrei Zimin, & Diana Velazquez**

Molar Mass is the weight of 1 mole of any element or compound.

How did the Avogadro Number come to be 6.022x10^23

Periodic Table

Important

For most problems, you have to round the atomic mass and the molar mass to the nearest (tenth) 0.1 g/mole. HOWEVER, make sure that you use at least as many sig figs in your molar mass as the measurement with the fewest sig figs.

Finding Molar Mass of An Element

For any chemical compound that's not on the periodic table we need to find the molar mass of each atom that makes up the compound.

Molar Mass

How To Find the Molar Mass of Chemical Compounds

Practice

What is the molar mass of Lithium?

What is the molar mass of Ammonia?

The Avogadro Number originates from Carbon-12 as this element has an equal number of Neutrons, Protons, and Electrons. (1mol/12g C or 6.022 x 10^23). Furthermore, Carbon-12 is the most stable element on the periodic table.

1 mol of Li x (6.9 g of Li / 1 mol of Li) =

6.9 g/mol of Li

What is the molar mass of Sulfur?

1 mol of S x (32.06 g of S / 1 mol of S) =

32.06 g/mol of S

1 mol of N x (14.01 g of N / 1 mol of N)

+ 3 mol of H x (1.01 g of H / 1 mol of H) =

14.01 g/mol of N + 3.03 g/mol of H =

What is the molar mass of Carbon Dioxide?

1 mol of C x (12.01 g of C / 1 mol of C)

NH3

CO2

+ 2 mol of O x (16 g of O / 1 mol of O) =

12.01 g/mol of C + 32 g/mol of 0 =

44.01 g/mol of CO2

What is the molar mass of Sugar?

C6H12O6

6 mol of C x (12.01 g of C / 1 mol of C)

+ 12 mol of H x (1.01 g of H / 1 mol of H)

+ 6 mol of O x (16 g of O / 1 mol of O) =

72.06 g/mol of C + 12.12 g/mol of H + 96 g/mol of O =

180.18 g/mol of C6H1206

What is the molar mass of Nitric Acid?

HNO3

1 mol of H x (1.01 g of H / 1 mol of H)

+ 1 mol of N x (14.01 g of N / 1 mol of N)

+ 3 mol of O x (16 g of O / 1 mol of O) =

1.01 g/mol of H + 14.01 g/mol of N + 48 g/mol of O =

63.02 g/mol of HNO3

Molar Mass is also known as Avogadro's Number which is approximately 6.022 x 10^23.

The Molar Mass of the compound is equal to the molar mass of the atoms that make up the compound. That is why you need to find the molar mass of each atom.

What if there is a subscript in the chemical formula?

You would multiply the number of atoms that are next to the subscript by the number of the subscript.

For example: Iron (II)Chloride (FeCl2)

You have one atom of iron and two atoms of chloride. The molar mass will be equal to (1 atom x 56 grams/mole Fe) + (2 atoms x 35.5 grams/mole of chlorine) = 127 grams/mole of iron (II) chloride.

For example:

the molar mass of H2O

[1 mol of H x

(1.01 g of H/1 mol of H)

]

+

[2 mol of O x

(16 g of O/1 mol of O)

]

= 33.01 g/mol of H2O

The molar mass of elements is equivalent to the atomic mass of the element.

For a chemical compound that is not an element, you need to use the chemical formula.

The Molar mass of elements is found by looking at the atomic mass of the element on the periodic table.When you look up the atomic weight of gold,you find it is 196.966 g.Therefore, the molar mass of Gold is 196.97 g/mol.

H2O IS THE CHEMICAL FORMULA FOR A WATER MOLECULE. THE ELEMENTS OF OXYGEN AND HYDROGEN COMBINE TO MAKE WATER, WHICH IS CONSIDERED A COMPOUND BECAUSE IT CONSISTS OF MORE THAN ONE ELEMENT.

The molar mass of water is the mass of H2O. Add together the atomic masses of all of the atoms of hydrogen and water in a molecule of water.

2*1.008g (hydrogen)+1*16.00 g (oxygen)=18.02 g

+

= 18.02g

17.04 g/mol of NH3

MORE PRACTICE.

What is the molar mass of calcium carbonate (CaCO3)?

Solution:

Step 1.Look up the relative atomic mass of the atoms from the periodic table. Relative atomic mass (rounded to the nearest whole number):

Step 2: Calculate the relative formula mass.

Calcium carbonate (CACO3) contains one calcium atom, one carbon atom and three oxygen atoms.

Relative formula mass=40+12+(3*16)=100

Step 3.Express the relative formula mass in grams per mole.

The molar mass of ethanol is 100 g/mol

Work Cited

• http://misterguch.brinkster.net/molarmass.html

• http://www.occc.edu/kmbailey/chem1115tutorials/Stoichiometry_Molar_Mass.htm

• http://www.occc.edu/kmbailey/chem1115tutorials/Stoichiometry_Molar_Mass_Calculations.htm

• http://www.wikihow.com/Calculate-Molar-Mass

• http://www.chem.memphis.edu/bridson/FundChem/fund_toc.htm