2. What is a Mole?

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

4. 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.

5. 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

6. DO YOU GET THE IDEA?

7. 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 Sample problem ( Mole to mass conversion)

8. 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)

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

10. 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

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

12. ANSWERS 11. a) 96.3 g Al c) 203 g Co b) 1.20 x l0 3 g Si d) 1.60 x 10 2 Zn 12. a) 0.236 mol Ag c)1.91 mol Zn b) 9.355 mol S d) 17.9 mol Fe

13. SO NOW YOU KNOW A MOLE

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

15. Avagadro’s Number is 6.02 x 10 23 particles (particles includes atoms, molecules, ions, formula units)

16. This is a really big number 602 000 000 000 000 000 000 000

17. Conversion factors: 6.02 x 10 23 representative particles 1 mole OR ____________1 mole____________ 6.02 x 10 23 representative particles

18. moles gramsatoms X 1/ molar mass = X 6.02 x 10 23 = = 1/6.02 x 10 23 X = molar mass X X 1/molar mass X 6.02 x 10 23 = = molar mass X 1/6.02 x 10 23 X