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CHEMISTRY

CHEMISTRY. Feb 22, 2011. Warm Up. Find the molar mass of these substances Fe 3 N 2 Mg(OH) 2. Agenda. Warm Up Unit 8 Notes Intro to Moles and Stoichiometry Practice Problems Homework Unit 8 Worksheet 1 Reminder: Test Make Up Wednesday, Thursday, or Friday ONLY. Are these moles?.

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CHEMISTRY

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  1. CHEMISTRY Feb 22, 2011

  2. Warm Up • Find the molar mass of these substances • Fe3N2 • Mg(OH)2

  3. Agenda • Warm Up • Unit 8 Notes • Intro to Moles and Stoichiometry • Practice Problems • Homework • Unit 8 Worksheet 1 • Reminder: • Test Make Up • Wednesday, Thursday, or Friday ONLY

  4. Are these moles?

  5. 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

  6. What are the units of measurement? • "that equal number" of atoms randomly 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).

  7. 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

  8. 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

  9. Practice Problems • How many grams of Cu are in 1.20 mol of Cu? • How many moles are in 70g of Cl?

  10. 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?

  11. 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 4 mols of Hydrogen gas NOPE!!!! Fooled you.. 2 mols of Hydrogen gas

  12. Moles of atoms Volume of Gas at STP Representative Particles Representative Particles 1 mole 1 mole Mole Mole 1 mole 1 mole mol of atom 22.4 L 23 23 6.02x10 6.02x10 atomic atomic mol of atom 22.4 L 1 mole 1 mole 1 mole 1 mole mass mass 23 23 atomic atomic 1 mole 1 mole 6.02x10 6.02x10 mass mass 1 mole 1 mole Mass Mass Molecules Atoms Units Mole Conversion Boomerang

  13. 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

  14. White Boards • Given 200 g of water, how many mols of water do you have? • How many grams of carbon monoxide are in 1.5 mols of carbon monoxide?

  15. More conversion • Mole to atoms/molecules/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

  16. 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?

  17. More conversion • Mole to volume of gas or vice versa • What is the volume occupied by 2 mols of hydrogen gas? • Look at the boomerang: • Where do you begin? (the given: mols) • What do you need in the end? (volume of gas) • What’s the conversion factor? • 22.4 L of H2 1 Mols of H2 2.00 mols of H2 x 22.4 L of H2 = 44.8 L of H2 1 mol of H2

  18. White boards • Convert 4.38 moles of He to liters • Convert 3.01 L of N to moles

  19. Practice • 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?

  20. Homework • Mole Conversion Worksheet 1

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