# Mole Concept

Topics: Atom, Molecule, Mole Pages: 2 (365 words) Published: September 9, 2013
MOLE – Chemical unit of amount
* Refers to the amount of a substance which contains the same number of pieces as there are the number of atoms of Carbon in 12 grams of C12 12 grams C12 = 6.02 x 1023 atoms of Carbon = 1 mole

1 mole any substance = 6.02 x 10 23 pieces

1 mole of O atoms = 6.02 x 10 23 O atoms
1 mole Na atoms = 6.02 x 10 23 Na atoms
1 mole of H2O = 6.02 x 10 23 H2O molecules
1 mole of apples = 6.02x 1023 apples
Molar Mass – mass in grams of 1 mole of a substance
G atomic mass- mass in grams of 1 mole of atoms that is numerically equal to its atomic mass
22.9Na11
g-molecular mass – mass in grams of 1 mole of molecules that is numerically equal to its molecular mass (sum of all atomic masses of atoms comprising the molecule if the formula of the molecule is known) g – formula mass – mass in grams of 1 mole of formula units that is numerically equal to its formula mass ( sum of all atomic masses of atoms comprising the formula unit if formula of the compound is known)

MOLE = 6.02 X 10 23 = Molar mass

PROBLEM CATEGORIES OF THE MOLE CONCEPT
Category I : Conversions between mole , grams, atoms, molecules Calculation where information about the quantity of the substance is sought from a given quantity of the same substance.

E.g. How many moles of Na are present in 100 grams of Na ?
Category II : Calculation about Composition
Calculation where information about the quantity of substance is sought from a given amount of a compound containing the substance.

E.g. How many grams of Cl are contained in 20 grams of CCl4 ?

Other calculations :Percent Composition
Emperical Formula Determination
Molecular Formula Determination

Emperical Formula = formula which shows the smallest whole number ratio of atoms of the elements comprising the compound. Molecular Formula = formula which shows the actual number of atoms of the elements comprising the compound. Category III : Stoichiometry- Quantitative...