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What’s up with the Mole?

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How do we measure matter? By weight: We buy bananas by the _______________. By volume: Milk is sold by the ____________________. By counting: There are ________ students in class. pound gallon

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Chemical Quantities Many words are used to express a specific quantity. Pair = Dozen = 2 12

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How do we measure matter? What if I wanted to know how many ATOMS were in this copper penny? Would you like to count? Could you?

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Avogadro’s Number You can count particles if you introduce a term that represents a specified number of particles. In chemistry, the term used to express a specific number of particles is a mole.

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Avogadro’s Number 1 mole = 6.02 x 10 23 particles 602,000,000,000,000,000,000,000 That’s 602,000,000,000,000,000,000,000 A very large number!

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Avogadro’s Number This number is known as Avogadro’s number, named after Amedeo Avogadro (an Italian physicist and mathematician).

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n 1 mole of hockey pucks would equal the mass of the moon! n 1 mole of pennies would cover the Earth 1/4 mile deep!

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Representative Particles Representative particles are units used to measure the number of particles in a sample of an element or compound. Substance Representative Particle elementatom covalent compoundmolecule ionic compoundformula unit

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Representative Particles What is the representative particle for each of these substances? copper sodium chloride water atom molecule formula unit

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MOLE A mole is the SI unit that measures the amount of a substance. A mole can be related to: number of particles mass volume of a gas

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mass in grams using the periodic table Avogadro’s number of particles 22.4 L of a gas one mole

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MOLE Use dimensional analysis to convert: – moles to molecules – moles to atoms – moles to formula units – moles to grams – grams to atoms – and many more….

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MOLE When converting between moles and particles, the conversion factor to remember is: 1 mol = 6.02 x 10 23 particles The particle unit can be atoms, molecules, or formula units.

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Mole/Particle Examples 1. How many moles are in 3.25 X 10 20 atoms of lead? 3.25 x 10 20 atoms Pb 1 mol = 6.02 x 10 23 atoms 6.02 x 10 23 atoms Pb 1 mol Pb = 5.398671 x 10 -4 = 5.40 x 10 -4 mol Pb

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Mole/Particle Examples 2. How many molecules are there in 8.3 moles of sugar (C 12 H 22 O 11 )? 8.3 mol C 12 H 22 O 11 1 mol = 6.02 x 10 23 molecules 6.02 x 10 23 molec. C 12 H 22 O 11 1 mol C 12 H 22 O 11 = 5.0 x 10 24 molec. C 12 H 22 O 11 = 4.9966 x 10 24

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Mole/Particle Examples 3. How many atoms are in 0.425 mol sulfur? 0.425 mol S 1 mol = 6.02 x 10 23 atoms 6.02 x 10 23 atoms S 1 mol S = 2.56 x 10 23 atoms of S = 2.5585 x 10 23

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Mole/Particle Examples 4. How many moles are in 5.42 x 10 22 formula units of NaCl? 5.42 x 10 22 Form. U NaCl 1 mol = 6.02 x 10 23 atoms 6.02 x 10 23 Form. U NaCl 1 mol NaCl = 0.090033222= 0.0900 mol NaCl

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Molar Mass molar mass – the mass in grams of one mole of an element or compound.

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Terms that Describe the Mass of a Substance Atomic mass – mass of one atom of an element (unit = amu) Molecular mass - mass of one molecule of a covalent compound (unit = amu) Formula mass - mass of one formula unit of an ionic compound (unit = amu) Molar mass - mass of one mole of an element or compound (unit = g/mol).

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Molar Mass To calculate molar mass: 1.Obtain all of the masses of the involved elements from the periodic table. 2.Multiply each element’s mass by the subscript. 3.Add the resulting products. 4.Round the answer to the proper number of decimal places.

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Molar Mass of Element Examples Aluminum = Zinc = 26.982 = 26.98 g/mol 65.38g/mol

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Molar Mass of Compounds Examples Diphosphorus pentaoxide P2O5P2O5 P = O = 30.974 15.999 X 2 X 5 = 61.948 = 79.995 + 141.943= 141.94 g/mol

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Molar Mass of Compounds Examples Aluminum Hydroxide Al(OH) 3 Al = O = 26.982 15.999 X 1 X 3 = 26.982 = 47.997 + 78.003= 78.00 g/mol H = 1.008X 3= 3.024 +3

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Molar Mass of Compounds Examples Barium phosphate Ba 3 (PO 4 ) 2 Ba = P = 137.328 30.974 X 3 X 2 = 411.984 = 61.948 + 601.924 = 601.92 g/mol O = 15.999 X 8 = 127.992 +2-3

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Moles to Mass Use dimensional analysis to convert – moles to mass or mass to moles. Mass unit = grams Conversion Factor to Remember: – 1 mol = molar mass of the element or compound (molar mass = g/mol) found on the periodic table

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Moles to Mass Examples How many moles of carbon are in 26 g of carbon? 26 g of C Carbon: 1 mol = 12.01 g (from PT) 1 mol of C 12.01 g of C = 2.2 mol of C = 2.164862614

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Moles to Mass Examples How many grams are there in 2.37 moles of CO 2 ? 2.37 mol CO 2 C = 12.011 x 1 O = 15.999 x 2 44.01 g CO 2 1 mol CO 2 = 104 g CO 2 = 104.3037 = 12.011 = 31.998 + 44.009 g = 1 mol

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Moles to Mass Examples How many moles are present in 142.1 grams of NaCl? 142.1 g NaCl Na = 22.990 x 1 Cl = 35.453 x 1 1 mol NaCl 58.44 g NaCl = 2.432 mol NaCl = 2.43155373 = 22.990 = 35.453 + 58.443 g = 1 mol

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Moles to Mass Examples How many grams are in 3.34 moles of potassium bromide? 3.34 mol KBr K = 39.098 x 1 Br = 79.904 x 1 119.00 g KBr 1 mol KBr = 397 g KBr = 397.46 = 39.098 = 79.904 + 119.002 g = 1 mol +1 KBr

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Molar Volume of a Gas The volume of a gas changes as the temperature and pressure change, so the volume is usually measured at standard temperature and pressure. STP = abbreviation for standard temperature and pressure Standard temperature = 0 o C = 273 K Standard pressure = 1 atm or 101.3 kPa

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Molar Volume of a Gas At STP, one mole of any gas occupies the same volume: 22.4 L.

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Molar Volume of a Gas Use dimensional analysis to convert: – volume (liters) to moles – or moles to volume (liters) Conversion Factor to Remember: – 1 mole = 22.4 L

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Molar Volume of a Gas Examples Determine the volume, in liters, of 0.60 mol SO 2 gas at STP.

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Molar Volume of a Gas Examples Assuming STP, how many moles are in 67.2 L SO 2 ?

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Molar Volume of a Gas Examples How many moles are in 1.0 x 10 3 L of C 2 H 6 ?

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Molar Volume of a Gas Examples What is the volume at STP of 3.20 x10 -3 mol CO 2 ?

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Mole Calculations Learned MOLES # of Particles (atoms, molecules, formula units) Mass (grams) Liters of gas at STP 1 mol = 6.02 x 10 23 particle s 1 mol = 22.4 L 1 mol = mass from Periodic Table

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