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Homework:

Homework:. Read Pages 58-61 Do all of % composition worksheet Mole problems 3 Packet Next Quiz: Monday Feb 25 or Tues Feb 26 Test: March 11 th (Monday) or March 12 th (Tuesday). Percent Composition Lesson 3.

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Homework:

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  1. Homework: • Read Pages 58-61 • Do all of % composition worksheet • Mole problems 3 Packet • Next Quiz: Monday Feb 25 or Tues Feb 26 • Test: March 11th (Monday) or March 12th (Tuesday)

  2. Percent Composition Lesson 3 • Determining the formula of a compound % by mass of each element in a compound

  3. % Composition If 8.20 grams of magnesium combines with 5.40 grams of oxygen to form a compound , what is the % composition of this compound?

  4. % composition 9.03 grams of Mg combine completely with 3.48 grams of nitrogen

  5. % Composition of a known compound

  6. % composition of C3H8

  7. % composition of each element in sodium bisulfate

  8. Homework • Read: pages 59-61 • Worksheet: Finding Empirical and Molecular Formulas • More Mole problems WS II # 1-6 • Test: March 11th and 12th

  9. Mole Problems 3 • 5.6 Liters • 3.00 moles • 8.03 grams • 38.5 Liters • 1.3 g/L

  10. Mole Problems 4 • 170 grams • 2.53 grams • 22.8 grams • 2.75*1023 atoms • 106 grams

  11. Mole Problems 5 • 9.21*1022 molecules NaOH • 40.9 grams • 2.07 L • 3*10-23 grams

  12. Percent Composition 1. HCN 3. Ca(NO3)2 3.74% H 24.42% Ca 44.43% C 17.07% N 51.83% N 58.50% O 2. H2O 4. Al2(CO3)3 11.21% H 23.06% Al 88.79% O 15.40% C 61.54% O

  13. More Mole Problems Question 1 Question 5 9.20 x 10-17 g 2.11 x 1023 atoms Question 2 Question 6 0.5648 moles area = 0.00645 cm3 = 0.00645 mL Question 3 3.89 x 1020 atoms 1.694 moles 1.02x1024 atoms Question 4 • 2.1 x 1023 molecules • 183 g

  14. More Mole Problems Question 7 • 5.1 mol • 1.86 x 1025 atoms • 182 mL Question 8 4.36x1016 molecules Question 9

  15. Finding Empirical and Molecular Formulas Question 1Question 4 • C3H4O3 CH2Cl C2H4Cl2 • CH2O Question 5 • CH2O C4H5N2O Question 2 CH5N empirical CH5N molecular Question 3 Question 6 P2O5 SN empirical; S4N4 molecular

  16. More Mole Problems Worksheet No.3 Answers • 2) STP: 0°C, 1 atm (760 mmHg, 101.3 kPa) • 3) 1.96 g/L • 4) 6.19 x 1022 molecules • 5) 20 moles • 6) 19.97% • 7.a) 5.78 x1022 atoms • 7.b) 0.384 g • 7.c) air: 1.25 g/L; bag: 1.365 g/L,  bag will not float • 8) 4.70% • 9) 5 glasses

  17. Empirical Formula • Lowest whole number ratio of atoms of the elements in a compound.

  18. Calculate the empirical formula of a compound that is 25.9% nitrogen and 74.1% oxygen • Step 1: find mole ratio • Step 2: divide by least # of moles • Step 3: multiply to get a whole number

  19. Molecular Formulas • Molecular formulas are whole number multiples of the empirical formulas • The empirical formula and the MM of the molecular formula is needed!

  20. What is the empirical formula of a compound that is 27.3% C and 72.7% O?

  21. Calculate the molecular formula given the empirical formula is CO2 and has a molar mass of 132.03 grams/mol • Find the MM of the empirical formula • Divide the MM of the molecular formula by the MM of the empirical formula • Multiply all elements by the whole # to get the molecular formula

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