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THE MOLE

THE MOLE. derryasd.schoolwires.com/725493911205633/lib/.../THE_ MOLE .ppt. Molar Masses:. The _____ of the masses of all the elements in a chemical formula expressed in _____ unit per ______. H 2 O 2(1 g/mol) + 16 g/mol = 18 g/mol H 2 SO 4 2(1 g/mol) + 32 g/mol + 4(16 g/mol) = 98 g/mol.

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THE MOLE

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  1. THE MOLE derryasd.schoolwires.com/725493911205633/lib/.../THE_MOLE.ppt

  2. Molar Masses: • The _____ of the masses of all the elements in a chemical formula expressed in _____ unit per ______. • H2O 2(1 g/mol) + 16 g/mol = 18 g/mol • H2SO4 2(1 g/mol) + 32 g/mol + 4(16 g/mol) = 98 g/mol

  3. Moe’s Mall: Map of finding masses, parts and volumes. BULK FOOD STORE “Consume MASS quantities” Anything with gram units Parts Store ‘Parts is Parts’ [atoms, ions, formula units, molecules, etc.] Molar Mass of X: g/mol Avogadro’s Number of X :6.02 x 1023 [MOlEs] Molar Volume of X: 22.4 L /mol Music Store ‘Turn up the VOLUME” [mL, L, etc]

  4. Sample Calculation: Mass(X)  Mol(X) Mass(X) (_____________________________) Mol(X) • g  mol • 50.4 g Ca Br2 = ? mol • 50.4 g Ca Br2 x 1 mole = .252 mol 200 g CaBr2

  5. Sample Calculation: Mol(X) Mass(X) Mol(X)(__________________________)  Mass(X) • mol  g • 1.26 mol NaCl = ?g • 1.26 x 58.5 g = 73.7 g • 1 mol

  6. Sample Calculation: Number(X) Mass(X) Number(X) (_____________________) Mol(X) (______________)  Mass(X) • particles  grams • 7.74 x 1026 formula units of Al2O3 = ? g • 7.74 x 1026 x 1 mol x 102 g = 1.31 x 105 g 6.02 x 1023 1 mol

  7. 10.3 PERCENT COMPOSITION • It helps to know the ______________composition of the components in a shirt because they affect how warm it is, whether it will need to be ironed, and how it should be cleaned.

  8. PERCENT COMPOSITION • In a chemical compound the percent composition determines the _______________of that compound • relative mass of each _________, or _________ of elements in relationship to the entire ________________ • mass of __________ x 100 = % composition mass of _____________

  9. 10.3 Percent Composition of a Compound • The percent by _________ of an element in a compound is the number of mass of the ____________ divided by the mass in grams of the __________________, multiplied by 100%.

  10. (ex) Mass Percents of Fe & O in Fe2O3 • Mass of Fe 2 (55.8 ) = 111.6 amu • Mass of O 3 (16.0) = 48.0 amu • Mass of Fe2O3 159.6 amu • ___________________________________ • % Fe 111.6 amu x 100  70 % 159.6 amu • % O 48.0 amu x 100  30 % 159.6 amu

  11. EMPIRICAL FORMULAS • ____________________ chemical formulas • _________________ cannot be divided by a common number (other than one).

  12. CALCULATING EMPIRICAL FORMULAS • 1] Determined using % composition data • 2] % used as ________ and then converted to ___________ • 3] Divide by ____________ number of moles • 4] If Necessary, ___________ to get Mole ratios reduced to __________ numbers [subscripts]

  13. Sample Calculation • Analysis shows water to be 88.8% oxygen and 11.2 % hydrogen by mass. • What is the empirical formula? • In every 100 g sample: • 88.8 g of O and 11.2 g of H.

  14. Assuming a 100 g sample..Use Molar Masses: • 88.8g = 5.55 moles O 11.2 g = 11.2 moles H 16.0 g/mol 1.0 g/mol • Mole Ratio = 5.55 : 11.2, Divide both by 5.55 • reduces to 1 O : 2 H ratio • Used as the subscripts • EF= H2O

  15. MOLECULAR FORMULAS • Expresses the chemical formula as it actually exists in ______________. • Is the ____________ as, or a ___________ of the empirical formula.

  16. 10.3 Molecular Formulas methanal(CH2O), ethanoic acid(C2H4O2), and glucose(C6H12O6) all have the __________ empirical formula—CH2O.

  17. CALCULATING MOLECULAR FORMULAS • 1] Know, or be able to calculate the ___________ formula. • 2] Know, or be given the ___________ mass • 3] Divide _______________ mass by mass of the ____________ formula • 4] Multiply all __________________ by this factor

  18. Given: 92.3% C, 7.7% H, Molecular Mass of 26 g/mol • Calculate empirical formula • 92.3 g = 7.69 moles C 7.7 g = 7.7 moles H 12.0 g/mol 1.0 g/mol • 7.69 : 7.7 • 1 mol C: 1 mol H • CH • empirical formula mass = 13 g/mol • molecular mass = 26 g/mol [26 / 13= 2] • Molecular Formula: CH x 2 = C2H2

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