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The Mole Honors Chemistry Are these moles? What is a mole? A unit of measurement Since the numbers in chemistry are so small, we use a “preferred unit of measurement” (mole) to represent the small number What are the units of measurement? "that equal number" of atoms arbitrarily chosen. the number of atoms in the atomic weight in g of any element. the number of atoms in 16 g of oxygen, in 4 grams of He, in 32 g of sulfur, etc. the number of molecules in the molecular weight, in grams, of any compound. the number of molecules in 18 g of water, in 40 g of lithium carbide. Much later, a mole, that equal number, was found to be 6.022 x 1023(representative particles). Examples 1 mole (or abbr. mol) = 12.011 g of Carbon 1 mol of Carbon = 6.02 x 1023 atoms of C 1 mol of H2O = 6.02 x 1023 molecules of water 1 mol of NaCl = 6.02 x 1023 units of NaCl Figure 8.1: All these samples of pure elements contain the same number (a mole) of atoms: 6.022 x 1023 atoms. Copyright © Houghton Mifflin Company.All rights reserved. 8–5 Moles in mass 1 mole can equal the atomic weight of an element. 1mol of C = 12.011g of C 1 mole can equal the atomic weight of a compound 1mol of CO = 12.011g of C + 15.99 g of O = 28.0 g of CO Group Whiteboards How many grams are in 1 mol of Nitrogen? Dinitrogen monoxide? **How many mols are in 100g sample of N2O? Warm Up #8 How many grams of Cu are in 1.20 mol of Cu? How many moles are in 70g of Cl? Moles in compounds Let’s say you have water aka. H2O How many moles of Hydrogen atoms(ions) are in water? Ask yourself how many individual atoms of Hydrogen do you see in water? Did you say 2??? Is that your final answer? You are correct! So how many mols of Oxygen atoms do you see? Moles in an equation 2 H2 + O2 2H2O How many moles of Hydrogen molecules are in the reactants? *Coefficients serve as the number of moles too! Therefore, there are 2 mols of Hydrogen gas Molecules Atoms Units Mole Conversion Boomerang Mole Conversions Mass to mole or vice versa: How many moles are in 24 g of Carbon? Look at the boomerang: Start with the given: 24 g (mass) of C What do you want in the end? Moles of C Use the conversion factor given: 1 mole Atomic mass 24 g of C x 1 mol of C = 2.0 mol of Carbon 12.011 g of C Brain Teaser Given 200 g of water, how many molecules of water do you have? How many liters of carbon dioxide are in 1.5 x 10^33 molecules of carbon dioxide? More conversion Mole to particles or vice versa How many atoms are in 2.00 mols of Carbon? Look at the boomerang: Where do you begin? (the given: mols) What do you need in the end? (atoms: particles) What’s the conversion factor? 6.02 x 1023 Atoms of C 1 Mols of C 2.00 mols of C x 6.02 x 1023 atoms of C = 1.20 x 1024 atoms C 1 mol of C White boards How many molecules of oxygen gas are in 3.0 mols of Oxygen gas? How many mols of Oxygen gas are in 4.67 x 1024 molecules of Oxygen gas? Final conversion!!! Mole to moles of atoms or vice versa If you have 2.00 mols of water, how many moles of hydrogen atoms are there? Look at the boomerang: Mols mols of atoms(ions) CF: mols of H+ atoms mols of water 2.00 mols of H2O x 2 mols of H+ atoms = 1 mol of H2O = 4.00 mols of H+ atoms Final conversion!!! Mole to Volume (gas) or vice versa Any gas at STP (standard temperature and pressure) has a volume of 22.4L per mole Look at the cloud chart: Mols volume of gas CF: Moles of gas 22.4L of gas Ex. How much volume of gas is in 5.00 moles of H2? 5.00 moles H2 x 22.4 L of H2 1 mole of H2 = 122 L of H2 Rally table Must show work (dimensional analysis) How many grams are in 1 mol of Mercury? Given a 1.5 mols of carbon dioxide, how many molecules of carbon dioxide do you have? Given 3.00 mols of carbon tetraflouride, how many mols of Flourine atoms are there in a compound?