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Warm-Up List as many counting terms as you can. A counting term is a word that represents a specific number Ex: Pair = 2 Dozen = 12 Score = 20 Gross = 144 Mole = 6.02 x 10 23

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CH 7 The Mole and Chemical Compounds Avagadro’s Number The mole Mole Conversions Percent Composition Empirical Formula

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The mole – like a dozen only bigger Equal to the number of atoms in 12.0g of carbon-12. 1 Mole = 6.02 x 10 23 particles Also known as: Avagadro’s Number After Italian physicist Amadeo Avogadro

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Chemistry particles An atom Na, Li, He A molecule O 2, H 2 O, CCl 4 A formula unit (this is what you call a “molecule” of an ionic substance) NaCl, MgO, H 2 SO 4

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Conversions A conversion factor is a form of the number 1. Multiplying by it only changes the units. Multiply using the conversion factor with the units you WANT on the top.

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How many eggs in 5 dozen? How many score in 90 years?

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How many atoms are there in 2.0 mol of sodium? How many atoms in 3.5 mol of sodium?

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How many molecules are there in 2.5 mol of sulfur dioxide? How many atoms are there in 2.5 mol of sulfur dioxide?

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Label each of the following atom, molecule, or formula unit (F.U.), or ion Sodium Metal: Na Oxygen gas: O 2 Water: H 2 O Sodium Chloride: NaCl Iron (III): Fe 3+ Phosphorus Trichloride: PCl 3 Methane: CH 4

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Solve on Whiteboard, show work How many atoms are there in 0.02mol of Iron? How many atoms are there in 0.02mol of Water? How many moles are there in 9.03x 10 24 molecules of water?

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“molecular weight” “molar mass” The mass of one mole of an element or compound. Determine the mass using the atomic mass from the periodic table. (numerically equal to atomic mass) atomic weightmolar mass Sodium22.99 amu22.99 g Magnesium24.30 amu g

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How to calculate molar mass 1. Use the atomic mass from the periodic table. 2. Add up the atomic masses for each element in the compound. NaCl = 22.99g + 35.45g 58.44 grams/mole Ex. H 2 O 2 Hydrogens x 1.0g + 1 Oxygen x 16.0g 18.0 grams/ mole

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Find the molar mass of the following compounds CO 2 LiF Na 2 S HCl KClO

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Warm-Up What is the molar mass of Sulfur Trioxide S = 1 x 32.1 O = 3 x 16.0 80.1 g/mol

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Find the molar mass of Acetic Acid HC 2 H 3 O 2 What is the mass of 2 moles of acetic acid?

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Writing/abbrevieating:Mole Mole mol (don’t read this as “molecule”) n 2.0 moles of Carbon = 24.02g 2.0 mol Carbon = 24.02g 2.0 n Carbon = 24.02g

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Determine the molar mass NH 3 What is the mass of 3 moles of NH 3 14+1+1+1 = 17 g/mol 3mol x 17 g/mol = 51g

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Determine the mass of 1.75mol Uranium 0.7mol SF 6

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Determine the mass of 1. 0.720 mol Be 2. 2.40 mol N 2 3. 4.52x10 -3 mol C 20 H 42 4. 5.08 n Calcium Nitrate Find the number of moles in 1. 5.00g of Hydrogen gas (H 2 ) 2. 11.0 g of methane (CH 4 ) 3. 333g of Tin (II) Fluoride

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Converting #Particles to Mass 1. Divide the number of particles by Avagadro’s # to get moles. 2. Multiply the #moles by molar mass to get grams Find the mass of 2.44 x 10 24 atoms of Carbon.

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Calculate the mass slates path: Particles Moles Mass 5.3 x 10 23 atoms of Molybdenum (Mo) 1.299 x 10 26 ions of Nitrate (NO 3 - ) 6.12 x 10 14 formula units of Rhenium Oxide (ReO 2 )

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Calculate the # of Particles slates path: Mass Mole Particles How many atoms in 54.3g of Cobalt (Co) ? How many molecules in 245g of Oxygen gas (O 2 )? How many molecules in 0.0923g Hydrgen Fluoride gas (HF)?

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Molar Volume of a gas

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Molar volume of a gas The volume of 1 mole of a gas (any gas) at Standard Temperature and Pressure (STP) is 22.4 Liters. [the volume of 45 water bottles] The standard conditions (STP) are: Temp: 0 C Pressure: 1.0 atmosphere

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Calculate the volume of the following @ STP: 2.0 moles of Oxygen 3.5 moles of oxygen 3.5 moles of Carbon Dioxide

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Warm UP In a 10.O gram Oreo cookie, the cream has a mass of 2.0 grams. What is the % composition (by mass) of the cookie?

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Calculate % Composition *from lab data 1. Add the masses of each element to find the total mass. 2. Divide the mass of one element by the total mass, multiply by 100 (then add % sign) 3. Repeat step 2, for each element 4. Add up all the %s to make sure they = 100%

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An 8.2 gram piece of Mg combines with 5.4 grams of Oxygen. What is the % composition? 1. Add the masses to find the total. 2. Divide the mass of one element by the total mass. Multiply by 100 (add %) 3. Repeat for other elements. 4. Do the %’s add to 100?

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Calculate % composition *from the chemical formula What is the percent composition of Propane, C 3 H 8 ? 1. Assume you have 1 mole of the substance. 2. Determine molecular mass of the substance. 3. Divide the mass of one element by the molecular mass. Multiply by 100. (add ‘%’) 4. Repeat for other elements in the substance. 5. Do the %s add to 100?

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Determine the percent composition Of water.

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Warm Up Determine the % Composition of MgCl 2 If you have 100g of magnesium chloride how many grams of magnesium are there? If you have 84g of magnesium chloride how many grams of magnesium are there?

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Empirical Formulas: The empirical formula may or may not give the actual formula. For any compound, its empirical formula is the lowest whole number ratio of elements.

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Empirical Formula form molecular formula CompoundChemical FormulaEmpirical Formula (lowest whole number ratio) Hydrogen Peroxide H2O2H2O2 HO GlucoseC 6 H 12 O 6 C ? H ? O ? Acetic AcidC2H4O2C2H4O2 AmmoniaNH 3

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Empirical Formula Use lab data to determine ratio of elements.

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Calculating empirical formula *from lab data (% comp data) The % composition is 20.1% Hydrogen and 79.9% Carbon. Determine the empirical formula. 1. Assume 100g total (easy conversion from %) So: 20.1g of Hydrogen 79.9g of Carbon

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2. Determine the number of moles of each element. Convert the grams of each element to a number of moles. 20.1 g H /1.01 g/mole _____ moles of Hydrogen 79.9 g C / 12.01 g/mole ____moles of Carbon

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C H Subscripts must be whole numbers. 3. Divide each amount of moles by the smallest number. C H

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Warm-Up What is the empirical formula for Oxalic Acid?H 2 C 2 O 4 Empirical formula is the lowest whole number ratio of elements in a compound.

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A chemical compound has the empirical formula CH 2 O The molar mass of the compound is 180g/mol What is the molecular formula?

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