1. Mass Relationships The Mole and Stoichiometry

2. The Mole A mole is the number of atoms in exactly 12 grams of 12 C (carbon-12 isotope)A mole is the number of atoms in exactly 12 grams of 12 C (carbon-12 isotope) One mole is equal to 6.02x10 23 particlesOne mole is equal to 6.02x10 23 particles A particle will be an atom(elements) or molecule(compounds)A particle will be an atom(elements) or molecule(compounds) The number 6.02x10 23 is known as Avogadro’s numberThe number 6.02x10 23 is known as Avogadro’s number

3. Molar Mass The mass of one mole of any chemical substance is numerically equal to the periodic table weight of the substanceThe mass of one mole of any chemical substance is numerically equal to the periodic table weight of the substance The gram mass of one mole of substance is known as the molar massThe gram mass of one mole of substance is known as the molar mass Molar mass has the unit grams per mole (g/mol)Molar mass has the unit grams per mole (g/mol) Molar mass is used as a conversion factor between gram and mole valuesMolar mass is used as a conversion factor between gram and mole values

4. Molar Mass What is the molar mass of carbon dioxide?What is the molar mass of carbon dioxide? –Formula: CO 2 Formula mass: 44 amu –Molar Mass: 44 g/mol

5. Molar Mass What is the molar mass of carbon dioxide?What is the molar mass of carbon dioxide? –Formula: CO 2 Formula mass: 44 amu –Molar Mass: 44 g/mol

6. Conversions using molar mass Convert 5.0 g of CO 2 to moles of CO 2Convert 5.0 g of CO 2 to moles of CO 2 –Divide 5.0 g by the molar mass –5.0 x 1 mole = 0.114 moles CO 2 – 44 g

7. Conversions using molar mass Convert 2.0 mol of CO 2 to grams of CO 2Convert 2.0 mol of CO 2 to grams of CO 2 –Multiply moles by the molar mass –2.0 mol x 44g = 88 g CO 2 – 1 mole

8. Conversions using Avogadro’s # Convert 2.0 mol of CO 2 to molecules of CO 2Convert 2.0 mol of CO 2 to molecules of CO 2 –Multiply moles by Avogadro’s # –2.0 mol x 6.02x10 23 = 2.4x10 24 CO 2 molecules – 1 mole

9. Conversions using Avogadro’s # Convert 2.0x10 26 mol of CO 2 to moles of CO 2Convert 2.0x10 26 mol of CO 2 to moles of CO 2 –Divide moles by Avogadro’s # –2.0 26 CO 2 x 1 mole = 330 CO 2 molecules – 6.02x10 23

10. Quiz Time!

11. Make the following computations What is molar mass of water?What is molar mass of water? A) 12 g/molA) 12 g/mol B) 16 g/molB) 16 g/mol C) 18 g/molC) 18 g/mol D) 19 g/molD) 19 g/mol

12. Make the following computations What is the mass of 2 moles of water?What is the mass of 2 moles of water? A) 24 g/molA) 24 g/mol B) 36 g/molB) 36 g/mol C) 18 g/molC) 18 g/mol D) 9.0 g/molD) 9.0 g/mol

13. Make the following computations How many moles are in a 1.0 kg sample of water?How many moles are in a 1.0 kg sample of water? A) 56 g/molA) 56 g/mol B) 6.0 E23 g/molB) 6.0 E23 g/mol C) 18 g/molC) 18 g/mol D) 6.0 E26 g/molD) 6.0 E26 g/mol