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MEASURING MATTER

MEASURING MATTER. Chapter 10.1. COUNTING PARTICLES. Units exist that represent a specific number of items PAIR = 2 (gloves, shoes, socks) DOZEN = 12 (roses, eggs) REAM = 500 (paper) Appropriate for certain kinds of objects depending on the object’s size and function.

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MEASURING MATTER

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  1. MEASURING MATTER Chapter 10.1

  2. COUNTING PARTICLES • Units exist that represent a specific number of items • PAIR = 2 (gloves, shoes, socks) • DOZEN = 12 (roses, eggs) • REAM = 500 (paper) • Appropriate for certain kinds of objects depending on the object’s size and function

  3. Particles in chemistry • Atom / Element (one kind of atom) • Na, Mg, Pb, C • Molecules(covalent compounds = nonmetals) • CH4, H2O, SO2, CO2, H2, O2, N2, Cl2 • Formula Units (ionic compounds) • MgCl2, NaCl, Al(OH)3, (NH4)2SO3

  4. Mole • SI base unit used to measure the amount of a substance • Abbreviated as “mol” • Defined as the number of carbon atoms in exactly 12 g of carbon-12. • A mole of anything contains 6.02 x 1023 representative particles (atoms, molecules or formula units) • Avogadro’s number = 6.02 x 1023

  5. Converting between moles and particles • Conversion factor: a ratio of equivalent values used to express the same quantity in different units • 1 mol representative particles = 6.02 x 1023 representative particles • Conversion factors:

  6. Particles X (Atoms, Molecules or Formula Units) mol X

  7. Converting between moles and particles • If you are converting from moles to particles, you would use this conversion factor: • How many molecules of H2O are there in 5 moles of H2O ? 6.02 x 1023 molecules 1 mol 5 mol H2O x = 3.01 x 1024 molecules H2O

  8. Converting between particles and moles • If you are converting from particles to moles, you would use this conversion factor: • How many moles of NaCl are in a sample that contains 3.25 x 1024 formula units of NaCl? 1 mol 6.02 x 1023 formula units 3.25 x 1024 formula units NaCl x = 5.4 molNaCl

  9. Remember! • Representative particles must be replaced by one of the following: • Atoms (individual elements) • Molecules (covalent compounds) • Formula Units (ionic compounds)

  10. TODAY’s Assignments – 3/12/13 • Chapter 10.1 • Page 323 - #1-4 • Page 324 - #5-6 • Page 324 - #7-11 • Show all work and conversion factors for each problem

  11. 1 mol 6.02 x 1023 formula units

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