(4.3) The Mole and Molar Mass

THE MOLE IS THE SI UNIT FOR AMOUNT OF A SUBSTANCE. the mole represents 6.02 x particles. used for small particles such as atoms, electrons, molecules, ions, etc. this is called Avogadro’s Number. 602,000,000,000,000,000,000,000

in the same way that you can have a dozen (12) eggs or a pair (2) of shoes, you can have a mole (6.02 X ) of atoms or ions

A Mole of Particles A Mole of Particles Contains 6.02 x particles = 6.02 x C atoms = 6.02 x H 2 O molecules = 6.02 x NaCl “molecules” (technically, ionic compounds are not molecules so they are called formula units) 6.02 x Na + ions and 6.02 x Cl – ions 1 mole C 1 mole H 2 O 1 mole NaCl

MOLAR MASS

The Mass of a Mole moles of different substances have different masses just like a dozen tennis balls has a different mass than a dozen baseballs

Molar Mass (unit: g/mol) the mass of 1 mole (in grams) equal to the numerical value of the average atomic mass (get from periodic table) 1 mole of C atoms= g 1 mole of Mg atoms =24.31 g 1 mole of Cu atoms =63.55 g

Learning Check! Find the molar mass A. Br B. Sn =79.90 g/mol = g/mol

Molar Mass of Molecules and Compounds  mass, in grams, of 1 mole of a compound equals (numerically) to the sum of the individual atomic masses mass of 1 mole of CaCl 2 : 1 mole Ca X g/mol+ 2 moles Cl X g/mol = g/mol CaCl 2 = g/mol mass of 1 mole of N 2 O 4 :

Learning Check! A. Molar Mass of K 2 O = ? g/mol B. Molar Mass of antacid, Al(OH) 3 = ?