INTRODUCTION TO THE MOLE AND MOLAR MASS (OWLS & MOLES LAB)

Transcription

1 INTRODUCTION TO THE MOLE AND MOLAR MASS (OWLS & MOLES LAB)

2 BACKGROUND When you buy eggs you usually ask for a eggs. Dozen 12 You know that one dozen of any item is.

3 PAPER Paper is packaged in a. Ream A ream of paper has 500 sheets. Why is it useful to use units like a dozen or a ream?

4 What determines how many items should make up a particular unit?

5 If you were asked to design a new unit to count pieces of candy, what would you consider when choosing how many items should be included in your new counting unit?

6 ACTIVITY: WHAT YOU NEED: 3 packages, balance, worksheet, calculator, pencil.

7 PART 1 1. Follow your teacher s instructions:

8 DATA TABLE 1 Name of the Items in the Package Number of items in package Mass of items in the package

9 ANALYSIS AND INTERPRETATION As you know, a dozen represents 12 items. Since I did not have enough candy to put a dozen pieces in each bag, I decided to make a new counting unit. I called this unit an OWL. As you can tell, an Owl is 4 items.

10 1. A OWL OF ORANGES WILL HAVE 4 ORANGES.

11 2. A OWL OF PRETZELS HAS 4 PRETZELS.

12 3. A OWL OF MOLECULES OF WATER HAS 4 MOLECULES OF WATER.

13 4. A OWL OF ATOMS OF IRON HAS 4 ATOMS OF IRON. 26 Fe 55.85

14 Now that you understand the meaning of an OWL, you should be able to answer the following questions:

15 1. HOW MANY HERSHEY S KISSES ARE IN 2 OWLS? 8

16 2. HOW MANY DUM DUM POPS ARE IN 400 OWLS? 1600

17 3. HOW MANY STARBURSTS ARE IN 1/2 OWL? 2

18 4. HOW MANY HYDROGEN ATOMS ARE IN 6 OWLS? 24

19 Finding the Number of OWLS: If you are given the number of items you can tell the number of OWLS. For example, since one OWL is 4 items, 8 items make up 2 OWLS.

20 1. How many OWLS are 16 Hershey s Kisses? 4

21 2. How many OWLS are 100 pretzels? 25

22 3. How many OWLS are 400 Starbursts? 100

23 4. How many OWLS is 2 apples? ½ or 0.5

24 OWLS VS. MOLES An OWL of molecules of water would be too small to see. Scientists had to select a unit with a MUCH greater value for counting molecules because they are so small. The unit scientists use is called a MOLE.

25 ONE MOLE OF ANYTHING HAS THIS MANY ITEMS: 602,200,000,000,000,000,000,000

26 This number is written in Scientific notation to avoid mistakes: x 10 23

27 THIS IS KNOWN AS AVOGADRO S NUMBER x One MOLE of anything has x items.

28 1. HOW MANY HERSHEY S KISSES MAKE UP 1 MOLE? x 10 23

29 2. HOW MANY CARAMELS MAKE UP 10 MOLES? 10 [6.022 x ] x Or x 10 24

30 3. FIND THE NUMBER OF ATOMS OF SODIUM IN 2 MOLES. 11 Na [6.022 x ] x x 10 24

31 4. FIND THE NUMBER OF ATOMS OF CARAMELS IN 0.5 MOLES. 0.5[6.022 x ] x 10 23

32 5. HOW MANY MOLES ARE IN X OF STARBURSTS?. 1 mole

33 6. HOW MANY MOLES ARE IN X OF GOBSTOPPERS?. 2 moles

34 7. HOW MANY ATOMS OF POTASSIUM MAKE UP 1 MOLE? 19 K 1[6.022 x ] x

35 8. HOW MANY MOLECULES OF WATER MAKE UP 5 MOLES? 5[6.022 x ] x x 10 24

36 9. HOW MANY MOLES ARE IN X OF SODIUM? 11 Na 1 mole 22.99

37 10. HOW MANY MOLES ARE IN X OF CARBON? 6 2 moles C 12.01

38 11. HOW MANY MOLES ARE X MOLECULES OF WATER? 5 moles

39 PART 2

40 MASS In addition to being able to tell the number of items in an OWL, you can now tell the mass of an OWL of Hershey s Kisses, Jolly Ranchers, caramels, or whatever.

41 DATA TABLE 1 Name of the Items in the Package Candy #1 Candy #2 Candy #3 Number of items in package Mass of the package

42 USE THE CLASS AVERAGE DATA IN DATA TABLE 1 TO FILL IN THE INFORMATION BELOW: 1. BASED ON YOUR MEASUREMENTS, THE MASS OF 1 OWL OF CANDY #1 IS G. 2. THE MEASURED MASS OF 2 OWLS OF CANDY #1 IS G. 3. THE MASS OF 1 OWL OF CANDY #2 IS G. 4. THE MASS OF 1 OWL OF CANDY #3 IS G 5. THE MASS OF 100 OWLS OF CANDY #2 IS G. 6. THE MASS OF 1/2 OWL OF CANDY #3 IS G. 7. THE MASS OF 4 OWLS OF CANDY #2 IS G. 8. THE MASS OF 0.5 OWLS OF CANDY #3 IS G.

43 MASS OF A MOLE: As it turns out, the mass of one mole (6.022 X molecules or atoms of a substance) is THE SAME as the atomic weight of the molecule of the element as shown on the periodic table.

44 USE THE PERIODIC TABLE TO ANSWER THE FOLLOWING:

45 1. THE MASS OF 1 MOLE OF STRONTIUM (SR) IS G. 38 Sr 87.62

46 2. THE MASS OF 1 MOLE OF LEAD (PB) IS G. 82 Pb 207.2

47 3. THE MASS OF 1 MOLE OF NICKEL (NI) IS G. 28 Ni 58.69

48 4. THE MASS OF 4 MOLES OF STRONTIUM (SR) IS G Sr 87.62

49 5. THE MASS OF 0.5 MOLES OF LEAD (PB) IS G. 82 Pb 207.2

50 6. THE MASS OF 100 MOLES OF (NI) IS G Ni 58.69

51 MOLAR MASS Scientists also use the Periodic Table to determine the molar mass (formula weight) of compounds. The molar mass of the compound is the sum of the molar masses of the elements that make up the compound.

52 POTASSIUM CHLORIDE The molar mass of Potassium Chloride (KCl) is: Potassium (K) g/mole Chloride (Cl) g/mole g/mole

53 POTASSIUM PERMANGANATE The molar mass of KMnO 4 is the sum of all the molar masses times the number of atoms of each element for the molecule (subscript).

54 POTASSIUM PERMANGANATE KMnO 4 Potassium (K) Manganese (Mn) g/mole 54.94g/mole Oxygen (O) 4[16.00 g/mole] = 64.00g g/mole.

55 1. THE MOLAR MASS OF 1 MOLE OF SODIUM CHLORIDE (NACL) IS g Na = g Cl = g

56 2. THE MOLAR MASS OF 1 MOLE OF LEAD IODIDE (PBI 2 ) IS g. Pb = I = 126.9

57 3. THE MASS OF 100 MOLES OF NICKEL SULFIDE (NIS) IS g Ni = S = 32.06

58 4. THE MASS OF 1 MOLE OF IS GLUCOSE (C 6 H 12 O 6 ) IS g

59 5. THE MASS OF 1 MOLE OF IS SUCROSE (C H O ) g

60 6. THE MASS OF 4 MOLES OF IS GLUCOSE (C 6 H 12 O 6 ) IS g.