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The Mole

The Mole. 1 dozen =. 12. 1 gross =. 144. 1 ream =. 500. 1 mole =. 6.02 x 10 23. Avogadro’s Number. 6.02 x 10 23 is called “Avogadro’s Number” in honor of the Italian chemist Amadeo Avogadro (1776-1855). I didn’t discover it. Its just named after me!. Amadeo Avogadro. Page 291, #3.

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The Mole

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  1. The Mole 1 dozen = 12 1 gross = 144 1 ream = 500 1 mole = 6.02 x 1023

  2. Avogadro’s Number 6.02 x 1023 is called “Avogadro’s Number” in honor of the Italian chemist Amadeo Avogadro (1776-1855). I didn’t discover it. Its just named after me! Amadeo Avogadro

  3. Page 291, #3

  4. Page 291, #4

  5. Calculations with Moles:Using Avogadro’s Number How many atoms of lithium are in 3.50 moles of lithium? 3.50 mol Li 6.02 x 1023 atoms Li =atoms Li 2.11 x 1024 mol Li

  6. Page 292, #5

  7. Page 292, #6

  8. Review: Molar Mass A substance’s molar mass (molecular weight) is the mass in grams of one mole of the compound. CO2 = 44.0 grams per mole H2O = 18.0 grams per mole Ca(OH)2 = 74.0 g/mol

  9. Page 296, #s 7-8 PCl3

  10. Calculations with Moles:Converting moles to grams How many grams of lithium are in 3.50 moles of lithium? 3.50 mol Li 7.0 g Li = g Li 25 mol Li

  11. Calculations with Moles:Converting grams to moles How many moles of lithium are in 18.2 grams of lithium? 18.2 g Li mol Li =mol Li 2.6 7.0 g Li

  12. Calculations with Moles:Using Avogadro’s Number How many atoms of lithium are in 18.2 g of lithium? 18.2 g Li mol Li 6.02 x 1023 atoms Li 7.0 g Li mol Li (18.2)(6.02 x 1023)/7.0 =atoms Li 1.6 x 1024

  13. Standard Molar Volume Equal volumes of all gases at the same temperature and pressure contain the same number of molecules. - Amedeo Avogadro

  14. Standard Molar Volume

  15. Standard Temperature and Pressure“STP” • P = 1 atmosphere, 101.3 kPa • T = 0°C, 273 Kelvins • The molar volume of an ideal gas is 22.4 liters at STP

  16. Calculating Percentage Composition Calculate the percentage composition of magnesium carbonate, MgCO3. 24.0 g + 12.0 g + 3(16.0 g) = 84.0 g 100.00

  17. Formulas Empirical formula: the lowest whole number ratio of atoms in a compound. Molecular formula: the true number of atoms of each element in the formula of a compound. • molecular formula = (empirical formula)n [n = integer] • molecular formula = C6H6 = (CH)6 • empirical formula = CH

  18. Formulas(continued) Formulas for ionic compounds are ALWAYS empirical (lowest whole number ratio). Examples: NaCl MgCl2 Al2(SO4)3 K2CO3

  19. Formulas(continued) Formulas for molecular compoundsMIGHT be empirical (lowest whole number ratio). Molecular: C6H12O6 H2O C12H22O11 Empirical: H2O CH2O C12H22O11

  20. Empirical Formula Determination • Base calculation on 100 grams of compound. • Determine moles of each element in 100 grams of compound. • Divide each value of moles by the smallest of the values. • Multiply each number by an integer to obtain all whole numbers.

  21. Empirical Formula Determination Adipic acid contains 49.32% C, 43.84% O, and 6.85% H by mass. What is the empirical formula of adipic acid?

  22. Empirical Formula Determination(part 2) Divide each value of moles by the smallest of the values. Carbon: Hydrogen: Oxygen:

  23. Empirical Formula Determination(part 3) Multiply each number by an integer to obtain all whole numbers. Carbon: 1.50 Hydrogen: 2.50 Oxygen: 1.00 x 2 x 2 x 2 3 5 2 C3H5O2 Empirical formula:

  24. Finding the Molecular Formula The empirical formula for adipic acid is C3H5O2. The molecular mass of adipic acid is 146 g/mol. What is the molecular formula of adipic acid? 1. Find the formula mass of C3H5O2 3(12.0 g) + 5(1.0) + 2(16.0) = 73.0 g

  25. Finding the Molecular Formula The empirical formula for adipic acid is C3H5O2. The molecular mass of adipic acid is 146 g/mol. What is the molecular formula of adipic acid? 3. Multiply the empirical formula by this number to get the molecular formula. 3(12.0 g) + 5(1.0) + 2(16.0) = 73.0 g (C3H5O2) x 2 = C6H10O4

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