Weighing Carbon Can’t weigh individual atoms Define in terms of grams, not amu Reference: 12 g of carbon-12 Contains 6.02 x 1023 carbon atoms Avogadro’s Number = 1 mole

The McDondald’s Corporation: “Billions Served Daily” How big is a mole? The McDondald’s Corporation: “Billions Served Daily” How long to serve a mole? 6.022 x 1023 hamburgers 3.6 x 109 hamb/day = 1.67 x 1014 days = 458 billion years!

One Mole of: S C Hg Cu Fe

C 6 Atomic # Symbol Name Carbon MOLAR Mass (in g) 12.01

Molar mass is the mass of 1 mole of in grams marbles atoms eggs shoes Molar mass is the mass of 1 mole of in grams marbles atoms 1 mole 12C atoms = 6.022 x 1023 12C = 12.00 g 1 12C atom = 12.00 amu 1 mole C atoms = 12.01 g 1 mole lithium atoms = 6.941 g of Li For any element atomic mass (amu) = molar mass (grams)

Do You Understand Molar Mass? How many atoms are in 0.551 g of potassium (K) ? 1 mol K = 39.10 g K 1 mol K = 6.022 x 1023 atoms K 1 mol K 39.10 g K x x 6.022 x 1023 atoms K 1 mol K = 0.551 g K 8.49 x 1021 atoms K

molecular mass (amu) = molar mass (grams) Molecular mass (or molecular weight) is the sum of the atomic masses (in amu) in a molecule. SO2 1S 32.07 amu 2O + 2 x 16.00 amu SO2 64.07 amu For any molecule molecular mass (amu) = molar mass (grams) 1 molecule SO2 = 64.07 amu 1 mole SO2 = 64.07 g SO2

Do You Understand Molecular Mass? How many moles of C3H8O are in 72.5 g? 1 mol C3H8O = (3 x 12) + (8 x 1) + 16 = 60 g C3H8O 1 mol C3H8O 60 g C3H8O x 72.5 g C3H8O = 1.2 moles C3H8O

Do You Understand Molecular Mass? How many H atoms are in 72.5 g of C3H8O ? 1 mol C3H8O = (3 x 12) + (8 x 1) + 16 = 60 g C3H8O 1 mol C3H8O molecules = 8 mol H atoms 1 mol H = 6.022 x 1023 atoms H 1 mol C3H8O 60 g C3H8O x 8 mol H atoms 1 mol C3H8O x 6.022 x 1023 H atoms 1 mol H atoms x = 72.5 g C3H8O 5.82 x 1024 atoms H

Chemical Calculations 1 mole of CO2 = 6.02x1023 molecules CO2 Has a molar mass (M) of 12.01+16.00+16.00 = 44.01 g

So 1 mol of carbon weighs 12.01 g 1 mol of CO2 weighs 44.01 g 12.01g C . 44.01g CO2 x 100% = 27.3% If 3.3 Gt of C are put in the air: 3.3 Gt C x 44.01 Gt CO2 = 12 Gt CO2 put in the air 12.01 Gt C

Section 3.7 Chemical Reaction: Substances  new substances Chemical Equation: Symbols showing what happens

Physical states: sometimes omitted 2 Mg(s) + O2(g) 2 MgO(s) (Reactants) (Products) Physical states: sometimes omitted MUST be balanced!