Mole and Possible Conversion Factors.

S. 5.2 – The Mole

The mole: - - - -

Ex. -

Molar mass (g/mol): - - -

Ex.
|Element |Atomic mass shown on Periodic |Molar mass of element |
| |table | |
|N |14.0067 |14.0067 g |
|F |18.998403 |18.998403 g |
|P |30.97376 |30.97376 g |
|V |50.9415 |50.9415 g |
|Ni |58.69 |58.69 g |

Finding the molar mass of a compound. - Look up the molar masses of the elements within the compound using the periodic table. - Add up the masses and express in grams. - Round the molar masses to two decimal places. The more decimal the places the more precise your answer is.

Steps: 1) Determine how many atoms of each element are within the compound. 2) Determine the molar mass of each element. 3) Multiply the molar mass of each element by how many atoms of that element are within the compound. 4) Add up the numbers produced in step three.

Ex. 1: Calculate the molar mass of C6H4Cl2. 1) 6 C atoms, 4 H atoms, 2 Cl atoms 2) C = 12.01 g, H = 1.01 g, Cl = 35.45 g. 3) C = 6 × 12.01 g = 72.06 g, H = 4 × 1.01 g = 4.04 g, Cl = 2×35.45 g = 70.9 g. 4) 72.06 g + 4.04 g + 70.9 g = 147 g = molar mass = 1 mol C6H4Cl2