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Chapter 10.1

Chapter 10.1. The Mole: A Measurement of Matter. Three ways of measuring things…count, mass, & volume. Examples: soda—6 pack soda—liter grapes--lbs. Terms for specific counts…pair, dozen, etc. 1 dozen apples = 12 apples. 1 dozen apples = 2.0 kg apples.

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Chapter 10.1

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  1. Chapter 10.1 The Mole: A Measurement of Matter

  2. Three ways of measuring things…count, mass, & volume. • Examples: soda—6 pack • soda—liter • grapes--lbs

  3. Terms for specific counts…pair, dozen, etc. • 1 dozen apples = 12 apples. • 1 dozen apples = 2.0 kg apples. • 1 dozen apples = 0.2 bushels apples. • Ratios: 1 dozen apples/12 apples • 1 dozen apples/2.0 kg apples • 1 dozen apples/0.2 bushels apples

  4. Problem… • What is the mass of 90 apples if 1 dozen apples = 2.0 kg? • Analyze…known… • # of apples = 90 • 12 apples = 1 dozen • 1 dozen = 2.0 kg • Unknown…mass of 90 apples = ?kg

  5. Calculate

  6. Evaluate • Does it make sense? • Practice…What is the mass of 0.5 bushels of apples? • Practice…assume 8 seeds per apple. How many seeds are in 14 kg of apples?

  7. What is a Mole? • A specified number of particles. Used by chemists. 6.02 x 1023 representative particles (Avagrado’s number). • Representative particles can be atoms, molecules, or formula units. • Ratio: 1 mole/6.02x1023 rep. particles

  8. Scientific basis of the mole • 6.02x1023 is the number of atoms in 12 grams of Carbon-12. • If one mole of carbon-12 atoms were weighed, it would weigh exactly 12 grams.

  9. Atoms to moles • How many moles in 1.25x1023 atoms of magnesium? • Known; # of atoms = 1.25x1023 • 1 mole = 6.02x1023 atoms Mg. • Unknown; moles of magnesium. • Calculate…

  10. Moles to # of particles • How many atoms in a mole? First determine how many atoms in a representative particle. • How many atoms in 2.12 moles of propane (C3H8)? • Known: # of moles of C3H8 is 2.12. 1 mole = 6.02x1023molecules C3H8. 1 molecule C3H8 = 11 atoms. • Unknown: # of atoms.

  11. Calculate… • Practice… • How many atoms in 1.14 moles SO3? • How many moles in 4.65x1024 molecules NO2?

  12. The Mass of a Mole of an Element • Mass of atoms expressed in amu’s (atomic mass units), which are relative units based on the isotope Carbon-12 (12.0 amu). • C-12 is twelve times heavier than an average hydrogen atom with a mass of 1.0 amu. • 100 C-12 atoms are 12 times heavier than 100 hydrogen atoms.

  13. Any number of C-12 atoms are always twelve times heavier than the same number of hydrogen atoms. • The mass ratio of 12 carbon atoms to 1 hydrogen atom is the same regardless of the units used to express the mass. • Therefore, 12.0 g of carbon atoms and 1.0 g of hydrogen atoms must have the same number of atoms.

  14. Representative Particle • Smallest unit in a substance • Can be different things • One atom (metals, atomic substances) • One molecule (molecular compounds) • One ion (charged atoms or molecules) • One formula unit (ionic compounds)

  15. Examples of Representative particles

  16. Measuring Chemical Substances • Using Avogadro’s number: a specific number of representative particles 6.02 x 1023RP/mole • Referred to as one mole (mol) Example: One mol water contains • 6.02 x 1023 H20 molecules Example: one mole nitrogen gas…

  17. Practice Q: how many moles does 1.25 x 1023 atoms of Mg represent? A: 1.25 x 1023 Mg atoms x (6.03 x 1023 RP)/mole = 0.2 moles Q: how many moles does 2.8 x 1024 atoms of silicon have? A: 2.8 x 1024 Si atoms/6.03 x 1023 RP/mole = 4.6 moles Q:Q: How many propane (C3H8) molecules are in 2.12 mol of C3H8 ? A: 2.12 moles x (6.03 x 1023 )RP/mole = 12.8

  18. Converting molecular Moles into Number of individual atoms Hint: when asked for # of atoms always do Moles #molecules #atoms

  19. Practice Q: How many atoms are in 2.12 mol of C3H8 ? • First calculate how many molecules A: 2.12 moles x (6.02 x 1023 RP)/mole= 12.76 x 1023 RP = 1.28 x 1024 RP • Then calculate how many atoms Each RP (C3H8) has 11 atoms/RP Multiply with 11: 1.28 x 1024 RP x 11 Atoms/Rp= 14.08 X 1024 atoms • Clean all results to single digit number!!! 14.08 X 1024→ Atoms = 1.4 x 1025 atoms

  20. Practice You have 4.65 x 1024 molecules of NO2? Q: How many atoms? A: RP NO2 has three atoms/molecule 3 atoms/molecule x 4.65 x 1024 molecules

  21. The mass of one mole of a given element • Mass of an element is indicated in the periodic table as the mass number • Called amu = atomic mass unit • amu is the mass (in grams) of one mole of this element • Remember it is an average number of the different isotopes…it has decimals

  22. Finding mass • What is the mass of one mole O, P, K, S-33, 146C • Atomic oxygen: 16.00 g/mole • Atomic phosphorus: 30.97 g/mole • Atomic potassium: 39.10 g/mole • Atomic S-33: 33.00 g/mole • Atomic 146C: 14.00 g/mole

  23. How many mole in a given mass • How many moles of Carbon are found in 52 g? • 52 g/12.01 g/mole C= 4.33 moles C

  24. Practice calculating molar masses Q: How many moles of C-14 are found in 34 g? • 34 g x mole C-14/14g C-14 = 2.42 moles C-14 Q: What mass does 6.02 x 1023 atoms of Hydrogen have? • Is one mole → 1.01 g Q: What is the mass of 2.34 x 1022 atoms of phosphorus? First find how many moles 2.34 x 1022 atoms x mole/6.02 x 1023 atoms = 0.04 moles P 0.04 moles P x 30.97 g/mole = 1.24 g

  25. Mass of a Mole of a Compound • Example: SO3 • What type of compound? • How many atoms of S and O? • Add up amus of S and O • 32.1 amu + 16.0 amu +16.0 amu + 16.0 amu = 80.1 amu • One mole SO3 weighs 80.1 g

  26. Practice: find the molar masses Find the molar mass of • Water • Glucose • Carbon dioxide

  27. Practice Q:How many moles of glucose are in 200 g? • Molar mass of glucose is 180.18 g/mole A: 200g x mole/180.18 g = 1.11 moles Q: How many molecules of glucose is this? 6.02 x1023 RP/mole x 1.11 moles = 6.7 x 10 23 molecules glucose

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