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Proportions/Rates/Fractions

Proportions/Rates/Fractions . 1,500 pages in 12 days  =  ______   pages in 3 days 18 calls in 6 hours  =  ______   calls in 11 hours. Proportions/Rates/Fractions. 2,948 miles in 11 hours  =  ______   miles in 4 hours 68 seats in 4 rows  =  ______   seats in 8 rows. Molar Mass ( M ).

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Proportions/Rates/Fractions

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  1. Proportions/Rates/Fractions • 1,500 pages in 12 days  =  ______   pages in 3 days • 18 calls in 6 hours  =  ______   calls in 11 hours

  2. Proportions/Rates/Fractions • 2,948 miles in 11 hours  =  ______   miles in 4 hours • 68 seats in 4 rows  =  ______   seats in 8 rows

  3. Molar Mass (M) • the mass (m) of one mole of a substance • mass is measured in grams (g) • molar mass is grams per mole (g/mol) • The molar masses of allelements have been determined and can be found on the Periodic Table of the Elements. • all elements are different • molar masses of all elements are different

  4. M is molar mass (in g/mol) • m is mass (in grams) • n is number of moles • Avogadro’s number = 6.022 x 1023 • To find the number of atoms/molecules you multiply the # of moles by 6.022 x 1023 • If given # of atoms/molecules you divide by avogadro’s number.

  5. Solving mole calculations • 1. Find the Molar Mass • 2. Rewrite what is given, including the units • You should always have the 3 units, moles, grams, and g/mole. • If you have atoms/molecules you need to first convert to moles by dividing by avogadro’s number. • 2. Setup equal proportions/fractions • Numerators (tops) have the same units • Denominators (bottoms) have the same units • Solve for the unknown.

  6. What is the mass of 4.7 X 10-2 mol of LiBr.

  7. Determine the number of moles of substance 8.44 g of O2

  8. What is the mass of 3.45 X 1025 atoms of Zn

  9. How many atoms, molecules, or ions would be contained in 150 g of MgSO4

  10. Molar mass • The mass of one mole is called “molar mass” • E.g. 1 mol Li = 6.94 g Li • This is expressed as 6.94 g/mol • What are the following molar masses? S SO2 Cu3(BO3)2 32.06 g/mol 64.06 g/mol 308.27 g/mol Calculate molar masses (to 2 decimal places) CaCl2 (NH4)2CO3 O2 Pb3(PO4)2 C6H12O6 110.98 g/mol (Cax1, Clx2) 96.11g/mol(Nx2, Hx8, Cx1, Ox3) 32.00 g/mol (Ox2) 811.54 g/mol (Pbx3, Px2, Ox8) 180.18 g/mol (Cx6, Hx12, Ox6)

  11. g mol g/mol Formula g/mol g mol (n) Equation HCl 0.25 g= g/mol x mol H2SO4 53.15 NaCl 3.55 Cu 1.27 Converting between grams and moles • If we are given the # of grams of a compound we can determine the # of moles, & vise-versa • In order to convert from one to the other you must first calculate molar mass g = mol x g/mol mol = g  g/mol • Thiscanberepresentedinan“equationtriangle” 36.46 9.1 98.08 0.5419 mol= g  g/mol 58.44 207 g= g/mol x mol 63.55 0.0200 mol= g  g/mol

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