1. Dozen and Mole 1 dozen = 12 pieces 1/2 dozen of apples = 6 apples 2 dozens of eggs = 24 eggs 1 mole = 6.02 x 10 23 particles ½ mole of C atoms = 3.01 x 10 23 C atoms 2 moles of H 2 O molecules = 1.20 x 10 24 H 2 O molecules

2. Mole amount of substance containing the same number of particles as 12 g of C-12. 1 mole contains 6.02 x 10 23 particles (Avogadro’s number) Particles – may be atoms, molecules, ions

3. Mole and Number of Particles 1 mole of any substance contains 6.02 x 10 23 particles (atoms, molecules, ions) 1 mole C-12 6.02 x 10 23 atoms 1 mole CO 2 6.02 x 10 23 molecules

4. Mole – Number of Particles Conversion MoleNumber of Particles x 6.02 x 10 23 particles/mole Sample Problem 1: How many molecules are there in 0.25 moles of H 2 O? 0.25 mol H 2 O x 6.02 x 10 23 molecules H 2 O mol = 1.505 x 10 23 molecules H 2 O

5. Mole – Number of Particles Conversion MoleNumber of Particles Sample Problem 2: How many moles are there in 1.2 x 10 24 molecules of H 2 O? 1.2 x 10 24 molecules H 2 O x 1 mole H 2 O 6.02 x 10 23 molecules H 2 O = 2.0 moles H 2 O / 6.02 x 10 23 particles/mole

6. Molar Mass 1 mole C-12 6.02 x 10 23 atoms 12 g 1 mole CO 2 6.02 x 10 23 molecules 44 g

7. Molar Mass What is the molar mass of Mg(OH) 2 ? Mg H O 1 mole2 moles2 moles 1(24g) = 24 g2 (1g) = 2g2 (16g) = 32g 24g+ 2 g +32 g = 58 g The molar mass of Mg(OH) 2 is 58g.

8. Mole –Mass Conversion MassMole / Molar Mass x Molar Mass Sample Problem 1 : What is the mass of 0.25 moles of H 2 O? Mass of H 2 O = 0.25 mol x 18 g mol = 4.5 g

9. Mole –Mass Conversion MassMole / Molar Mass x Molar Mass Sample Problem 2. How many moles are there in 36 g of H 2 O? Moles of H 2 O = 36 gx 1 mol 18g = 2.0 mol