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1 mole = 6.02 X 23 10 things This is called Avogadro’s number Molar mass Molar mass is the mass of a mole of that thing The molar mass of pennies is the mass of 6.02X1023 pennies (about 2X1024 grams) 2 million million million tons of pennies The molar mass of carbon is the mass of 6.02X1023 carbon atoms (which happens to be exactly 12 grams) Molar mass The molar mass of: Ca = 40.08 grams MgCl2 = 95.2 grams H2O = 18 grams (using the periodic table) Moles There are one mole of: Atoms in 40.08 grams of Ca (element) Formula units in 95.2 grams of MgCl2 (ionic) Molecules in 18 grams of H2O (molecular) Remember that representative particles refer to the types of substances we are measuring Moles 1 mole of atoms in 40.08 grams of Ca 3 moles of atoms in 95.2 grams of MgCl2 3 moles of atoms in 18 grams of H2O This will come in handy when we study chemical reactions. Moles Gram atomic mass (GAM) refers to the mass of one mole of atoms of an element Gram molecular mass (GMM) refers to the mass of one mole of molecules of a compound Gram formula mass (GFM) refers to the mass of one mole of formula units of an ionic compound 6.02 X 1023 remember this number Name Formula Representative particle Strontium Sr atom Iron Cobalt Silicon Aluminum Element 1 Element 2 Element 3 Sr - - Gram atomic mass (GAM) 87.6 g Name Magnesium sulfate Potassium iodide Calcium sulfite Lithium oxide Beryllium fluoride Representative Formula Element 1 Element 2 particle MgSO4 Formula unit Mg S Element 3 Gram formula mass (GFM) 4O 123.3 g Name Formula Carbon tetrachloride CCl4 Carbon monoxide Silicon dioxide Nitrogen Dihydrogen sulfide Representative Element 1 Element 2 particle molecule C Cl Element 3 Gram molecular mass (GMM) - 153.8 g How many moles in 26.8 grams of iron? How many moles in 26.8 grams of iron? We are given grams of iron, so that goes on the left We want moles, so that must end up on the right Make conversion factors do that How many moles in 26.8 grams of iron? 26.8 g Fe given mole Fe 55.85 g Fe Conversion factor How many moles in 26.8 grams of iron? 26.8 g Fe mole Fe 55.85 g Fe Cancel units in numerator and denominator How many moles in 26.8 grams of iron? 26.8 g Fe mole Fe 55.85 g Fe .48 mole Fe We will need to be able to figure out how many grams are in a certain number of moles. We use the same conversion factor as we just did, only inverted. How many grams in .48 moles of iron? How many grams in .48 moles of iron? .48 mol Fe given 55.85 g Fe mol Fe Conversion factor How many grams in .48 moles of iron? .48 mol Fe 55.85 g Fe Mol Fe Cancel units in numerator and denominator How many grams in .48 moles of iron? .48 mol Fe 55.85 g Fe mol Fe 26.8 g Fe Conversion factors: 12 in / 1 ft 1 ft / 12 in 5280 ft / 1 mi 1 mi = 1.61 km 1 mi / 5280 ft 1.61 km / 1 mi Conversion factors for calculating moles and grams: 12 g C / mol C Mol C / 12 g C 153.8 g CCl4 / mol CCl4 Mol CCl4 / 153.8 g CCl4 123.3 g MgSO4 / mol MgSO4 Mol MgSO4 / 123.3 g MgSO4 Things we’ll need to be able to do: • Write chemical formulas from chemical names – Magnesium sulfate is MgSO4 • Calculate molar mass from chemical formulas – 123.3 g MgSO4 is one mole MgSO4 • Use conversion factors to calculate moles from mass, and mass from moles – 123.3 g MgSO4 / mol MgSO4 – mol MgSO4 / 123.3 g MgSO4 How many grams in .06 mole potassium nitrate? How many grams in .06 mole potassium nitrate? • Formula? How many grams in .06 mole potassium nitrate? • Formula? • Molar mass? How many grams in .06 mole potassium nitrate? • Formula? • Molar mass? • Conversion factor? How many grams in .06 mole potassium nitrate? .06 mol KNO3 given 101 g KNO3 mol KNO3 conversion factor 6.06 g KNO3 How many moles in 486 grams aluminum sulfate? How many moles in 486 grams aluminum sulfite? • Formula? How many moles in 486 grams aluminum sulfite? • Formula? • Molar mass? How many moles in 486 grams aluminum sulfite? • Formula? • Molar mass? • Conversion factor? How many moles in 486 grams aluminum sulfite? 486 g Al2(SO3)3 given mol Al2(SO3)3 294 g Al2(SO3)3 conversion factor 1.65 mol Al2(SO3)3 1 mole of any element 6.02 X 1023 atoms of that element 1 molar mass of that element How many molecules in 287 grams carbon dioxide? How many molecules in 287 grams carbon dioxide? • Formula? How many molecules in 287 grams carbon dioxide? • Formula? • Molar mass? How many molecules in 287 grams carbon dioxide? • Formula? • Molar mass? • Conversion factor? How many molecules in 287 grams carbon dioxide? 287 g CO2 given 6.02 X 1023 molecules CO2 44 g CO2 conversion factor 3.93 X1024 molecules CO2 1. How many grams are in 2.73 moles of sodium chloride? 2. How many moles are in 682 grams of strontium nitrate? 3. How many representative particles are in .187 grams of copper(II) sulfate? 4. How many atoms are in 87.1 grams of magnesium chloride? 5. 239 grams of carbon tetrachloride is how many moles of molecules?