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I. Atomic Mass

I. Atomic Mass. The unit of an element is an atomic mass unit ( amu ). Carbon –12 has an atomic mass unit of 12 . The atomic masses of other elements are found by comparing them to carbon-12.

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I. Atomic Mass

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  1. I. Atomic Mass • The unit of an element is an atomic mass unit (amu). • Carbon –12 has an atomic mass unit of 12. The atomic masses of other elements are found by comparing them to carbon-12. • Average atomic mass –the average of the atomic masses of the naturally occurring isotopes of an element. REVIEW: WHAT’S AN ISOTOPE? 4. These are the numbers found on the periodic table.

  2. II. THE MOLE, AVOGADRO’S NUMBER, MOLAR MASS • A mole is the SI unit for the amount of substance. • A mole is like a dozen. • How many “things” are in a dozen?   • How many “things” are in a mole?

  3. II. THE MOLE, AVOGADRO’S NUMBER, MOLAR MASS • This number is called Avogardro’s Number. • Why was this number chosen? With this number of atoms, the mass in grams can be found on the periodic table EX: 1 mol H atoms = 1.0079grams (6.022x1023 atoms = mass from PT for each element)

  4. HOW MANY ATOMS IN EACH COMPOUND? • AgBr • C2H6 • NaHCO3 • Fe2O3 • Ca(OH)2 • Ca3(PO4)2

  5. Molar Mass Calculations Definition: the mass, in grams, of one mole of a substance. Example #1 NaCl

  6. Molar Mass #2 O2

  7. Molar Mass #3 C13H18O2 (ibuprofen)

  8. Molar Mass #4 Ca(NO3)2

  9. Exit 2/25/13: Calculate the molar mass: • K2SO4 • Al(OH)3

  10. III. CALCULATIONS WITH EXPONENTS Note: When typing powers of 10 in your calculator, NEVER type x 10. Instead, x 10 = EE or EXP button. For example, 2 x 102 you would type 2 EE/EXP 2. EXAMPLES: 1. (3.452x1024) = (6.022x1023) 2. (6.022x1023) x (23.45) =

  11. IV. CALCULATIONS (FACTOR LABEL PROBLEMS!) The arrows represent the necessary _______________________. STP:

  12. For gases at STP only! IV. CALCULATIONS (FACTOR LABEL PROBLEMS!)

  13. EXAMPLES: Mass-Mole: WHAT COVERSION FACTOR WILL YOU USE?

  14. EXAMPLES: Mass-Mole: • What is the mass in grams of 3.5 mol of the element copper, Cu?

  15. Mass-Mole: • A chemist produces 11.9g of aluminum, Al. How many moles of aluminum were produced?

  16. Mass-Mole: • How many moles of calcium chloride (CaCl2) are in 5.00g?

  17. Mass-Mole: • What is the mass in grams of 2.25 mol of ammonium hydroxide (NH4OH)?

  18. Mass-Mole: • How many moles are in 102.02g of calcium carbonate (CaCO3)?

  19. Mole-Particle: WHAT CONVERSION FACTOR WILL YOU USE?

  20. Mole-Particle: • How many moles of silver, Ag, are in 3.01x1023 atoms of silver?

  21. Mole-Particle: • How many atoms of aluminum chloride are in 2.75 mol?

  22. Mole-Particle: •  How many molecules are in 4.21moles of CO2?

  23. Mole-Particle: • How many atoms of sodium are in 2.75 mol?

  24. Mole-Particle: • How many moles are in 5.02x1023 molecules of water?

  25. Exit 3/1/13 • Calculate the number of grams in 0.63mol of hydrogen atoms (H2). • How many oxygen atoms (O2) are in 4.5mol?

  26. Warm-up • Find the number of moles in 5.62g of F2. • How many atoms is this?

  27. Mass-Mole-Particle: • What is the mass in grams of 1.20x108 atoms of copper?

  28. Mass-Mole-Particle: • How many atoms of sulfur are in 4.00g?

  29. Mass-Mole-Particle: • What is the mass in grams of 6.23x108 atoms of gold?

  30. Mass-Mole-Particle: • How many atoms are in 10.00g of silver?

  31. Mass-Mole-Particle: • What is the mass in grams of 3.45x1024 atoms of calcium?

  32. Mass-Mole-Particle: • How many atoms of tungsten are in 7.00g?

  33. Exit Slip • How many atoms of iron are in a 6.73g sample? • How many grams of He are in 2.0x1023 atoms?

  34. Volume of a Gas: • Determine the volume, in liters, of 0.60mol SO2 gas at STP.

  35. Volume of a Gas: • What is the volume of 0.960mol of CH4 at STP?

  36. Volume of a Gas: • How many moles are in 67.2L of SO2 at STP?

  37. Volume of a Gas: • Determine the moles of 0.880L of He at STP.

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