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The Mole

The Mole. 7.1 & 7.3. 7.1 Chemical Measurement:. Counting units: pair = 2 dozen = 12 score = 20 gross = 144 ream = 500 mole = ? 2. Counting atoms, molecules and grams are going to require much larger and much smaller numbers.

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The Mole

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  1. The Mole 7.1 & 7.3

  2. 7.1 Chemical Measurement: • Counting units: pair = 2 dozen = 12 score = 20 gross = 144 ream = 500 mole = ? 2. Counting atoms, molecules and grams are going to require much larger and much smaller numbers.

  3. 3. Remember the mass of an atom is measured in amu (atomic mass units) and the numbers on the Periodic Table are based on 1/12 of a carbon-12 atom. So from the table the mass of 1 carbon atom = 12.0 amu. This unit is very small, 1 atomic mass unit (amu) = 1.6605 x 10-24 g. Determine how many carbon atoms equals 12.0 grams:

  4. Determine how many phosphorus atoms equal 31.0 g:

  5. 4. This value is called Avogadro’s Number = 6.02 x 1023= 1 mole (602,000,000,000,000,000,000,000!) 5. A mole is the amount of a substance. It is based on the number of atoms of an element equal to the number of atoms in exactly 12.0g of carbon-12.

  6. Mole Analogies • An Avogadro's number of standard soft drink cans would cover the surface of the earth to a depth of over 200 miles. • If you had Avogadro's number of unpopped popcorn kernels, and spread them across the United States of America, the country would be covered in popcorn to a depth of over 9 miles. • If we were able to count atoms at the rate of 10 million per second, it would take about 2 billion years • 6.02 X 1023 Watermelon Seeds: Would be found inside a melon slightly larger than the moon.

  7. Mole Analogies • 6.02 X 1023 Donut Holes: Would cover the earth and be 5 miles (8 km) deep. • 6.02 X 1023 Pennies: Would make at least 7 stacks that would reach the moon. • 6.02 X 1023 Grains of Sand: Would be more than all of the sand on Miami Beach. • 6.02 X 1023 Blood Cells: Would be more than the total number of blood cells found in every human on earth.

  8. 6. Atomic mass: mass of one atom of an element measured in amu (atomic mass units). Ex #1)H = 1.0 amu O = 16.0amu C = 12.0amu 7. Formula mass: mass of all the atoms in a single molecule or formula unit of a compound. Ex #2) H2O = Ex #3) H2CO3 = H: 1.0 x 2 = 2.0 H: 1.0 x 2 = 2.0 O: 16.0 x 1 =16.0 + C: 12.0 x 1 = 12.0 18.0 amu O: 16.0 x 3 = 48.0 + 62.0 amu

  9. 8. Molar Mass: mass of one mole of an element The units used are g/mol. Round all elements’ masses to the tenths place. Ex #4)Elements: Cu = 63.5g/mol 1 mole Cu = 6.02 x 1023atoms Cl = 35.5g/mol 1 mole Cl = 6.02 x 1023atoms

  10. Ex #5)Covalent Compounds: H2O = 18.0g/mol 1 mole H2O = 6.02 x 1023molecules H2CO3 = 62.0g/mol 1 moleH2CO3 = 6.02 x 1023molecules

  11. Ex #6)Ionic Compounds: NaCl = 58.5g/mol 1 mole NaCl = 6.02 x 1023formula units MgO = 40.3g/mol 1 moleMgO = 6.02 x 1023formula units

  12. 9. Examples: N2 = 28.0g/mol = 6.02 x 1023molecules 2N2 = 56.0g/mol = 12.04 x 1023molecules 10. Practice: Calculate the molar mass of sucrose, C12H22O11. C: 12.0 x 12 = 144.0 H: 1.0 x 22 = 22.0 O: 16.0 x 11 = 176.0 + 342.0 g/mol

  13. Avogadro’s Number 11. 1 mole = 6.02 x 1023particles = molar mass 1 mole Ne = 6.02 x 1023 atoms Ne = 20.2g 1 mole CO2 = 6.02 x 1023molecules CO2= 44.0g 1 mole CaF2= 6.02 x 1023 formula units CaF2= 78.1g 12. The mole is the bridge between calculations of # of particles, mass and volume of a gas.

  14. 13. Conversion Factors:1 mole = 6.02 x 1023 particles (atoms, molecules or formula units)1 mole = molar mass (grams) from the periodic table May be used in a problem in one of two ways depending on the given units. Ex #1) Given 11.2 g of NaCl, how many moles does this represent?

  15. Ex #2) Given 2.50 moles of NaCl, how many grams does this represent?

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