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2. 2 Chemical Quantities or

3. 3 How you measure how much? How you measure how much? n You can measure mass, n or volume, n or you can count pieces. n We measure mass in grams. n We measure volume in liters. n We count pieces in MOLES.

4. 4 Moles n Defined as the number of carbon atoms in exactly 12 grams of carbon- 12. n 1 mole is 6.02 x 10 23 particles. n Treat it like a very large dozen n 6.02 x 10 23 is called Avogadro's number.

5. 5 Representative particles n The smallest pieces of a substance. n For an element it is an atom. –Unless it is diatomic n For a molecular compound it is a molecule. n For an ionic compound it is a formula unit.

6. 6 Volume Molecules Atoms Representative Particles Mass PT Moles 6.02 x 10 23 22.4 L Count

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8. 8 Conversion factors n Used to change units. n Two questions –What do you know? –Where do you need to go?

9. 9 Conversion factors Basic Equation: Given amount Unknown amount -------------------- X ------------------------- Recipe amount Recipe amount Don’t Forget: Keep same units top and bottom

10. 10 Calculation question n How many molecules of CO 2 are in 4.56 moles of CO 2 ?

11. 11 Calculation question n How many grams of water is 5.87 x 10 22 molecules?

12. 12 Gases and the Mole

13. 13 Gases n Many of the chemicals we deal with are gases. n They are difficult to weigh, so we’ll measure volume n Need to know how many moles of gas we have. n Two things affect the volume of a gas n Temperature and pressure n Compare at the same temp. and pressure.

14. 14 nElements that exist as gases at 25 0 C and 1 atmosphere

15. 15 Standard Temperature and Pressure n Avogadro's Hypothesis - at the same temperature and pressure equal volumes of gas have the same number of particles. n 0ºC and 1 atmosphere pressure n Abbreviated atm n 273 K and 101.3 kPa n kPa is kiloPascal

16. 16 At Standard Temperature and Pressure n abbreviated STP n At STP 1 mole of gas occupies 22.4 L n Called the molar volume n Used for conversion factors n Moles to Liter and L to mol

17. 17 Examples n What is the volume of 4.59 mole of CO 2 gas at STP?