IIIIIIIV The Mole I. Molar Conversions

A. What is the Mole? n A counting number (like a dozen) n Avogadro’s number n 1 mol = 6.02  items A large amount!!!!

n 1 mole of hockey pucks would equal the mass of the moon! A. What is the Mole? n 1 mole of pennies would cover the Earth 1/4 mile deep! n 1 mole of basketballs would fill a bag the size of the earth!

B. Molar Mass n Mass of 1 mole of an element or compound. n Atomic mass tells the...  atomic mass units per atom (amu)  grams per mole (g/mol) n Round to 2 decimal places

B. Molar Mass Examples n carbon n aluminum n zinc g/mol g/mol g/mol

B. Molar Mass Examples n water n sodium chloride H2OH2O  2(1.01) = g/mol  NaCl  = g/mol

B. Molar Mass Examples n sodium bicarbonate n sucrose  NaHCO 3  (16.00) = g/mol  C 12 H 22 O 11  12(12.01) + 22(1.01) + 11(16.00) = g/mol

C. Molar Conversions molar mass (g/mol) MASS IN GRAMS MOLES NUMBER OF PARTICLES 6.02  (particles/mol)

C. Molar Conversion Examples n How many moles of carbon are in 26 g of carbon? 26 g C 1 mol C g C = 2.2 mol C

C. Molar Conversion Examples n How many molecules are in 2.50 moles of C 12 H 22 O 11 ? 2.50 mol 6.02  molecules 1 mol = 1.51  molecules C 12 H 22 O 11

C. Molar Conversion Examples n Find the mass of 2.1  molecules of NaHCO  molecules 1 mol 6.02  molecules = 290 g NaHCO g 1 mol

C. Molar Conversion Examples n Find the mass of one Fe atom  1 mole Fe = 55.85g  1 mole Fe = 6.02 x atoms  g 1 mole 6.02 x atoms = 9.28 x g/atom 1 mole

C. Molar Conversions n How many Oxygen atoms are there in g of CaCO 3 ? 50.25g CaCO 3 1 mol CaCO g 3 mol O 1 mol CaCO x atoms O 1 mol O = 9.07 x atoms

IIIIIIIV …and if Avogadro rings, ask him to leave his number…

IIIIIIIV The Mole-Volume Relationship

The Volume of a Gas n Many of the chemicals we deal with are gases  They are difficult to weigh (or mass) n We need to know how many moles of gas we have n Two things effect the volume of a gas  Temperature and pressure n We need to compare gases at the same temperature and pressure

Standard Temperature and Pressure (STP) n 0°C and 1 atmosphere (atm) of pressure n At STP, 1 mole of any gas occupies 22.4 L, Called the molar volume n 1 mole = 22.4 L of any gas at STP

Practice examples n What is the volume of 4.59 mole of CO 2 gas at STP? n How many moles is 5.67 L of O 2 at STP? n What is the volume of 8.8 g of CH 4 gas at STP?

Molarity –Molar Volume of… Solutions! n Molarity = moles of solute/liter of solution n Note: it’s liters of solution, not liters of solvent

Molarity Examples n Calculate the molarity of a solution made by dissolving 23.4 g of sodium sulfate in 125 ml of solution n 23.4 g Na 2 SO 4  mol n 125 ml  L n M = mol / L n M = 0.165mol / L n M = 1.32 M

Molarity Examples n Calculate the molarity of a solution made by dissolving 5.00 g of C 6 H 12 O 6 in enough water to make ml of solution n M

Molarity Examples n How many grams of Na 2 SO 4 are required to make L of a M solution of Na 2 SO 4 ? n 24.9 g Na 2 SO 4