Concept A Mole Conversions

Topic 6: Stoichiometry Concept A - Mole Conversions

Page 1: Introduction to Mole Conversions

• Focus on understanding mole conversions.

Page 2: Lesson Objectives and Key Vocabulary

• Lesson Objectives:

  • Define a mole and its relation to Avogadro’s number.

  • Calculate the formula mass and molar mass using compound formulas.

  • Perform dimensional analysis for converting between moles, particles, mass, and volume.

• Key Vocabulary:

  • Atomic mass unit (amu): A unit of mass used to express atomic and molecular weights.

  • Average atomic mass: The weighted average of the atomic masses of an element's isotopes.

  • Mole: A unit defined as the amount of substance that contains the same number of entities as there are in 12 grams of carbon-12.

  • Avogadro’s number: 6.022 x 10^23, the number of particles in one mole of a substance.

  • Molar mass: The mass of one mole of a substance in grams per mole (g/mol).

Page 3: Molar Mass Definition

• Definition of Molar Mass:

  • A. Number of grams per one mole of a substance

  • B. Whole number ratio that is a multiple of a chemical formula

  • C. Simplest, whole number ratio of a chemical formula

  • D. 6.022 x 10^23 particles per one mole of a substance

Page 4: Relative vs Average Atomic Mass

• Relative Atomic Mass:

  • Atomic masses are expressed in relative atomic mass units (amu).

  • 1 amu = 1/12 the mass of a carbon-12 atom.

  • Carbon-12 has 6 protons and 6 neutrons, each with a mass of about 1.0 amu.

• Average Atomic Mass:

  • A weighted average of an element's isotopes, found on the periodic table.

Page 5: The Mole and Molar Mass

• Mole:

  • An SI unit measuring the amount of substance; 1 mole contains 6.022 x 10^23 particles (Avogadro's number).

  • Equivalent to the number of particles in 12g of carbon-12.

• Molar Mass:

  • Mass of one mole of a pure substance; units are g/mol.

  • Example: Molar mass of Lithium = 6.94 g/mol, equivalent to 6.94 amu.

• Sample Problem:

  • Calculate the molar mass of calcium (Ca) and calcium phosphate (Ca3(PO4)2).

  • Practice: Molar mass calculations for NH4NO3 and (CH3)2N2H2.

Page 6: Mole Conversions

• Mole conversions involve switching between moles, particles, grams, and volume using Avogadro's number and molar mass.

Page 7: Conversions - Sample Problems

• Mol/Gram Conversions:

  • a. Mass of 3.50 mol copper(II) sulfate?

  • b. Moles in 11.9 g aluminum nitrate?

• Mol/Particles Conversions:

  • c. Moles in 3.01 x 10^23 molecules of silver chloride?

  • d. Particles in 2.5 mol barium sulfate?

• Gram/Particles Conversions:

  • e. Mass in grams of 1.20 x 10^8 molecules of copper(I) cyanide?

  • f. Molecules in 4.00 g calcium sulfide?

• Volume/Moles/Mass Conversions:

  • g. Moles of hydrogen gas in 86.5 L at STP?

  • h. Volume of 158.72 g oxygen gas at STP?

Page 8: Conversions Practice Problems

• Carry out conversions:

  1. Mass of 2.6 moles of lithium bromide.

  2. Moles of iron(III) oxide equivalent to 452 g.

  3. Molecules in 4.00 moles of glucose (C6H12O6).

  4. Moles in 1.20 x 10^25 molecules of diphosphorous pentoxide.

  5. Mass of 4.00 x 10^23 molecules of calcium fluoride.

  6. Particles in a 1.43 g sample of cadmium nitrate.

  7. Nitrogen gas molecules in 3.36 L at STP.

  8. Volume of 2.00 x 10^23 molecules of fluorine gas.