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What is a mole? Stoichiometry The Mole Chemists use a measurement called ‘the mole’ A mole is like a dozen eggs= 12 eggs or a pair of shoes= 2 shoes However, the mole is a very large number This is because atoms are so small that chemists need a lot to be able to find their mass How big is the mole?? A mole contains 6.023 x 1023 of anything 6.023 x 1023 is a.k.a AVOGADRO’S NUMBER How big is a mole exactly? If you could count 10 million numbers every second, it would take you 2 billion years to count an avogadro’s number out If you had a mole of unpopped popcorn kernals it would cover the entire planet to a depth of 9 miles If you poured out a mole number of cans of pop out you would cover the entire earth with an ocean of pop 200 miles deep Therefore, 1 mole= 6.023 x 1023 particles or 6.023 x 1023 particles/mol 1 mole Cl= 6.023 x 1023 particles 1 mole of H= 6.023 x 1023 particles 2 moles= Atomic Molar Mass The mass (in grams) of 1 mole of a given element To find this for each element you must look at the periodic table: 1 mole of C= 12 g (or 12g/mol) What is the mass of 1 mole of oxygen? What about 2 moles of oxygen? 3 moles? Molecular Molar Mass Is the mass (in grams) of all the elements in the molecule To find the mass: 1. find each element’s atomic mass and 2. add all of the atomic masses together Ex NaOH: Na= 1 x 23 g/mol O= 1x 16 g/mol H= 1 x 1g/mol 40 g/mol of NaOH Ex H2O Ex. H2SO4 Find the following masses MgBr2, Ga(NO2)3, CrI2, BeSO4 Assignment: molar mass worksheet Stoichiometery Given two out of these three values for mass, moles and/or molar mass, you can figure out the value of the missing value Mass= moles x molar mass Moles= mass/molar mass Molar mass- find using periodic table Particles= moles x 6.023 x 1023 Examples Moles to mass 2.0 mol of CaO 0.6 mol of BeSe 1.35 mol of Li3P 0.35 mol of Be2SO4 Find moles given mass 18.02 g of H2O 80.92 g of HBr 5.0 g of CaCl2 0.26g of Ca3(PO4)2 15.0 g of MgCl2 86.7g of H3PO4 examples 1 mol, 1mol, 0.045 mol, 0.00084 mol,0.16 mol, 0.885 mol Assignments Assignment: molar mass/ moles/mass assignment examples Moles to particles: 1 mol of Fe 3 mols CO 0.671 mols H2O 0.1001 HBr 6.023 x 1023, 18.069 x1024, 4.04x 1023, 6.023x 1022 Particles to moles 6.023 x 1023 atoms of Fe 1.20 x 1023 atoms of O2 2.4 x 1024 atoms of H Examples 1.8 x 1024 atoms of K mol, 0.199 mol, 3.987 mol, 2.99 mol Examples Mass from particles mass of 1.20 x 1024 molecules of water? mass of 2.41 x 1024 atoms of barium hydroxide? mass of 1.51 x 1022 atoms of neon? mass of 7.53 x 1022 molecules of CH4? Particles from mass How many molecules does 36.0 grams of water represent? How many molecules does 11.0 grams of CO2 represent? How many atoms does 3.0 grams of carbon represent? How many formula units does 200.0 grams of calcium carbonate represent? assignment Stoichiometery problems with # of molecules Stoichiometery assignment with all the examples