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What is a Mole?

What is a Mole?. To a chemist a mole is a counting unit for a substance. Abbreviated “mol”. The mass of one MOLE of a pure substance is numerically equal to its ATOMIC MASS (the red number on the PT). We use grams to represent the unit for atomic mass. EXAMPLES.

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What is a Mole?

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  1. What is a Mole?

  2. To a chemist a mole is a counting unit for a substance. • Abbreviated “mol”

  3. The mass of one MOLE of a pure substance is numerically equal to its ATOMIC MASS (the red number on the PT). • We use grams to represent the unit for atomic mass.

  4. EXAMPLES ONE MOLE OF CARBON = 12.011 grams ONE MOLE OF LITHIUM = 6.941 grams ONE MOLE OF SODIUM = 22.98977 grams ONE MOLE OF GOLD = 196.967 grams

  5. DO YOU GET THE IDEA?

  6. Sample problem(Mole to mass conversion) • Calculate the mass in grams of 0.0450 moles of chromium. • Moles Cr x grams Cr = grams Cr mole Cr set up your conversion fraction so that mole Cr will cancel out

  7. 0.0450 mol Cr X 52.00 g Cr = 2.34 g Cr 1 mol Cr (make sure you set up your UNITS so they can cancel out)

  8. Now you work the practice problems on page 316 of text. 11. Determine the mass in grams of each of the following: • 3.57 mol Al c) 3.45 mole Co • 42.6 mol Si d) 2.45 mol Zn

  9. Mass to Mole Conversions • Calcium, the fifth most abundant element on Earth, is always found combined with other elements because of its high reactivity. How many moles of calcium are in 525 grams calcium (Ca)? mass in grams x 1 mole= number of moles mass in grams • 525 grams Ca x 1 mole = 13.1 moles 40.08 grams Ca

  10. PRACTICE PROBLEMS • 12. Determine the number of moles in each of the following. • 25.5 g Ag c) 125 g Zn b) 300.0 g S d) l.00 kg Fe

  11. ANSWERS • 11. a) 96.3 g Al c) 203 g Co • b) 1.20 x l03g Si d) 1.60 x 102 Zn • 12. a) 0.236 mol Ag c)1.91 mol Zn • b) 9.355 mol S d) 17.9 mol Fe

  12. SO NOW YOU KNOW A MOLE

  13. AmedeoAvagadro Was an Italian physicist & lawyer who established that ONE MOLE of ANYTHING contains 6.02 x 10 23representative particles.

  14. Avagadro’s Number is6.02 x 10 23 particles(particles includes atoms, molecules, ions, formula units)

  15. This is a really big number602 000 000 000 000 000 000 000

  16. Conversion factors:6.02 x 10 23 representative particles 1 moleOR____________1 mole____________6.02 x 10 23representative particles

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