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# Chem class(27feb)

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### Chem class(27feb)

1. 1. 4S6Welcome To my Chemistry Class~
2. 2. Number of particles Number of Avogadro Moles c onstant Particles= Atoms, molecules, ions Avogadro constant = 6.02 x 1023(Mary No Car)1. Number Of Particles = number of moles x Avogadro constant2. Number Of Moles = number of particles ÷ Avogadro constant
3. 3. RECALL BACK….  1 mole of Carbon = 6.02 x 1023 atoms  1 mole of H20 = 6.02 x 1023 molecules  1 mole of Fe2+ = 6.02 x 1023 ions  1 mole of O2 = 6.02 x 1023 molecules = 2 x 6.02 x 1023 atoms
4. 4. CALCULATE THE NUMBER OF ATOMS IN 3 MOLOF COPPER ATOMS. CuNumber of Atoms= Number of mole x Avogadro Constant= 3 x 6.02 x 1023= 1.806 x 1024 mol of copper atoms
5. 5. CALCULATE THE NUMBER OF MOLECULE IN 0.5MOL OF CO2 O C ONumber of molecule= Number of mole x Avogadro Constant= 0.5 x 6.02 x 1023= 3.01 x 1022 mol of carbon dioxide
6. 6. Calculate the number of Ions in 0.5 molof Pb2+ Pb2+Number of ions= Number of mole x Avogadro Constant= 0.4 x 6.02 x 1023= 2.408 x 1022 mol of Pb2+
7. 7. CALCULATE THE NUMBER OF ATOMS IN 0.5 MOLOF CO2 O CNumber of atoms O= Number of mole x Avogadro Constant= 3 x 0.5 x 6.02 x 1023= 9.03 x 1023 mol of carbon dioxide atoms
8. 8. EXAMPLE 2:a. Calculate the number of moles of atoms in 1.204 x 1025 iron atoms.b. Calculate the number of moles of ions in 6.02 x 1021 copper(II) ions, ____c. Given 1.505 x 1024 oxygen gas, , calculate i) the number of moles of oxygen molecules, ii) the number of atoms of oxygen atomsd. Given 2.408 x 1025 hydrogen atoms, calculate i) the number of moles of hydrogen atoms. ii) the number of moles of hydrogen molecules,
9. 9. A.CALCULATE THE NUMBER OF MOLES OFATOMS IN 1.204 X 1025 IRON ATOMS.Number of Moles= Number of particles Avogadro Constant= 1.204 x 1025 6.02 x 1023= 20 mol of iron atoms
10. 10. B.CALCULATE THE NUMBER OF MOLES OF IONS IN6.02 X 1021 COPPER(II) IONS, ____Number of Moles= Number of particles Avogadro Constant= 6.02 x 1021 6.02 x 1023= 0.01 mol of copper(II) ions
11. 11. C. GIVEN 1.505 X 1024 OXYGEN GAS, , CALCULATE I) THE NUMBER OF MOLES OF OXYGEN MOLECULES, Number of Moles = Number of particles Avogadro Constant = 1.505 x 1024 6.02 x 1023 = 2.5 mol of Oxygen molecules
12. 12. C. GIVEN 1.505 X 1024 OXYGEN GAS, , CALCULATEII) THE NUMBER OF ATOMS OF OXYGEN ATOMS2 x 1.505 x 1024= 3.01 x 1024 oxygen atoms O O O O O O O O 1 O2 molecule = 2 O atoms
13. 13. D. GIVEN 2.408 X 1025 HYDROGEN ATOMS, CALCULATE I) THE NUMBER OF MOLES OF HYDROGEN ATOMS. II) THE NUMBER OF MOLES OF HYDROGEN MOLECULES,i) Number of Moles= Number of particles Avogadro Constant= 2.408 x 1025 6.02 x 1023 H= 40 mol of hydrogen atoms Hii) 40 mol of hydrogen atoms ÷2 H = 40 H = 20 mol of hydrogen molecules
14. 14. NOTE: The gases which exist as diatomic molecules are: O2 H2 N2 Cl2 Br2 I2 Cl Cl O H O H I I
15. 15. 3.3 THE MOLE AND THE MASS OF SUBSTANCESA. The molar mass - is the mass of one mole of any substance. The molar mass of a substance = the mass of 1 mole _______ of substance = the mass of ____________ particles. -the unit of molar mass is ________. 12 1 mol of carbon-12 has a mass of exactly _____g. 12 So, the molar mass of carbon-12 is __________.
16. 16. THE MOLAR MASS OF ALL THE OTHER SUBSTANCESARE NUMERICALLY EQUAL TO THEIR RELATIVEMASSES. Examples: The relative atomic mass of sodium = 23, so, the 23 molar mass of sodium = ____________ The relative atomic mass of water, so, the molar 18 mass of water = ____________
17. 17. Mass Number of Relative atomic Moles Mass/ RMM(Mario Miss Rainbow)
18. 18. EXAMPLE 1: a. Calculate the mass of 2 mol of carbon atoms b. Calculate the mass of 5 mol of oxygen gas, c. calculate the mass 0.4 mol of magnesium oxide, MgO.
19. 19. CALCULATE THE MASS OF 2 MOL OFCARBON ATOMSThe molar mass of carbon atoms = 12gmol-1so, the mass of 2 mol of carbon atoms = 2 mol x 12gmol-1 = 24g
20. 20. CALCULATE THE MASS OF 5 MOL OFOXYGEN GASthe mass of 5 mol of oxygen gas = 5 mol x 32gmol-1 = 160g
21. 21. Calculate the mass 0.4 mol of magnesium oxide, MgO.The molar mass of MgO = 24+16 = 40gmol-1The mass of 0.4 mol of magnesium oxide = 0.4 mol x 40gmol-1 = 16g
22. 22. ANSWERa) The molar mass of carbon atoms = 12gmol-1 so, the mass of 2 mol of carbon atoms = 2 mol x 12gmol-1 = 24gb) The molar mass of oxygen gas = 2(16) = 32gmol-1 so, the mass of 5 mol of carbon atoms =5 mol x 32gmol-1 = 160gc) The molar mass of MgO = 24+16 = 40gmol-1 so, the mass of 0.4 mol of MgO = 0.4 mol x 40gmol-1 = 16g
23. 23. EXAMPLE 2: a. How many moles of atoms are there in 18g of carbon? b. How many moles of sodium chloride are there in 14.625g of sodium chloride, NaCl? c. Given 6.4g of oxygen gas, calculate i) the number of moles of oxygen gas. ii) the number of moles of oxygen atoms.
24. 24. How many moles of atoms are there in 18g of carbon?The molar mass of carbon atoms = 12gmol-1The number of moles of carbon atoms = 18 g 12gmol-1 = 1.5mol
25. 25. How many moles of sodium chloride are there in 14.625g of sodium chloride, NaCl?The molar mass of sodium chloride, NaCl= 23 + 35.5=58.5gmol-1So, the number of moles of NaCl =14.635 g 58.5gmol-1 =0.25mol
26. 26. OGiven 6.4g of oxygen gas, calculatei) the number of moles of oxygen gas. OThe molar mass of Oxygen gas = 2(16) = 32gmol-1So, the number of moles of oxygen gas = 6.4 g 32gmol-1 = 0.2mol
27. 27. II) THE NUMBER OF MOLES OF OXYGEN ATOMS.ii) The number of moles of oxygen atoms O = 2 x 0.2 mol = 0.4 mol O
28. 28. ANSWER:a) The molar mass of carbon atoms = 12gmol-1 The number of moles of carbon atoms = 18 g 12gmol-1 = 1.5molb) The molar mass of sodium chloride, NaCl = 23 + 35.5 = 58.5gmol-1 So, the number of moles of carbon atoms=14.635 g 58.5gmol-1 = 0.25molb) i) The molar mass of Oxygen gas = 2(16) = 32gmol-1 So, the number of moles of oxygen gas = 6.4 g 32gmol-1 = 0.2mol ii) The number of moles of oxygen atoms = 2 x 0.2 mol = 0.4 mol
29. 29. EXAMPLE 3: a. Calculate the mass of 6.02x 1021 iron atoms. b. How many molecules of oxygen are there in 12.8 g of oxygen gas?
30. 30. a. Calculate the mass of 6.02x 1021 ironatoms. FeNumber of moles= 6.02 x 1021 6.02 x 1023= 0.01 molThe mass of 6.02x 1021 iron atoms= 0.01mol x 56gmol-1= 0.56g
31. 31. How many molecules of oxygen are thereOin 12.8 g of oxygen gas? Number of moles O= 12.8 g 32gmol-1= 0.4 molNumber of molecule of oxygen= 0.4 x 6.02 x 1023= 2.408 x 1023 molecules of oxygen
32. 32. ANSWER:a. 6.02 x 1021 iron atoms = 6.02 x 1021 6.02 x 1023 = 0.01 mol0.01 mol of iron atoms = 0.01mol x 56gmol-1 = 0.56gb) 12.8g of oxygen gas = 12.8 g 32gmol-1 = 0.4 mol0.4mol of oxygen gas = 0.4 x 6.02 x 1023 = 2.408 x 1023 molecules of oxygen
33. 33. PASS UP THURSDAY(28/2/2013)
34. 34. Cl- Zn2+ Cl-1 ZnCl2 = 1 Zn2+ ion 2 Cl- ions