Unit 8 Moles & Percent Composition Chapter 10

Words representing Numbers Dozen12 Baker’s Dozen13 Gross144 Ream500 Mole6.02 x 10 23

Avogadro’s Number 6.02 x Number of representative particles in a mole 1 mol He = 6.02 x atoms 1 mol H 2 = 6.02 x molecules

Practice 2 mol H 2 = x molecules 2 mol H 2 = x atoms 2 mol H 2 O = x atoms 2 mol C 6 H 12 O 6 = x O atoms

Mole-Mass relationship 1 mole of any element equals the atomic mass in grams 1 mol Carbon = 12.01g Carbon 1 mol Iron = 55.8g Iron

Gram Formula Mass Mass of the formula in g/mol Simply add the atomic masses of each element in the formula together H 2 O = = 18 g/mol Also known as gram atomic mass, gram molecular mass, molar mass

Rounding Round most masses to the nearest whole gram Except: Copper, Cu  63.5 Chlorine, Cl  35.5

Practice KNO 3 = (3) = 101 g/mol C 6 H 14 = 12(6) + 1(14) = 86 g/mol CuSO 4 = (4) = g/mol

Mole - Mass Conversion Example: 96 g of Oxygen gas = ? mol

Practice How many moles are there in 506g of ethanol, C 2 H 6 O? What is the mass of 8 moles of CCl 4 ? 1232g CCl 4 11 mol C 2 H 6 O

Mole Road Map

Review How many moles are in 584g of SF 6 ? How many grams are in 6 mol of HCl? X = 584g 146 g/mol = 4 mol 6 mol = X 36.5 g/mol = 219 g

Percent Composition

Example H 2 O H 11.1% H O 88.9% O

Another Example NH 3 N 82.4% N H 17.6% H

Percent Composition What is the percent composition of oxygen in H 2 SO 3 ? 58.5%

Percent Composition What is the percent composition of aluminum in Al 2 (SO 4 ) 3 ? 15.8%

Percent Composition What is the percent composition of nitrogen in NH 4 NO 3 ? 35%