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2. 6.02 x 1023 So…. When chemists talk about a “mole,” what exactly are they talking about??? Ummm… I don’t think so... THAT’S IT! Cute… but no… Not quite…

3. That’s right, in chemistry, a “mole” is a number! Just like a “dozen” is 12 and a “gross” is 144, a “mole” is simply a word that stands for a number: 6.02 x 1023

4. So… What is so special about the number 6.02 x 1023? For one thing, it represents a very, very, VERY large quantity. If written out, it would be: 602,000,000,000,000,000,000,000. That’s 602 million, million, billion! That’s big!

5. How big you ask… Consider the following examples. (And come up with your own if you want. They’re really not that hard to do…)

6. This computer has a remarkably fast processor: 1.83 GHz. That means, for example, that it is capable of counting to 1,830,000,000 every second! So… at that rate, how long do you think it would take this computer to count to 1 mole???

7. By the way, factor label makes this calculation fairly simple: At 1,830,000,000 per second, it would take this computer a little over ten million years to count to 1 mole!! (That’s a lot of counting!) 1sec 1.83x109counts 1min 60 sec 1hr 60 min 1 day 24 hr 1 year 365 day 6.02 x 1023counts X X X X X = 1.04 x 107 years = 10.4 million years

8. A grain of rice is pretty small. It takes about fifty grains of rice to fill a tiny one-milliliter box! Even still, one mole of rice grains would be HUGE… Take a guess: How much space would be taken up by one mole of rice grains?

9. over 23 meters deep! And… in case you were wondering how this was calculated: 1 mL 50 grains 1 m3 1 x 106mL Volume of all that rice Area that rice has to cover X X = 1.2 x 1016 m3 6.02 x 1023 grains One mole of rice – that’s 6.02 x 1023 grains – would cover the entire planet Earth… Earth’s radius = 6400 km = 6.4 x 106 m Surface area of a sphere = 4Pr2 Surface area of Earth = 4P(6.4 x 106m)2 = 5.1 x 1014 m2 1.2 x 1016 m3 5.1 x 1014 m2 Volume Area = Height = = 23.5 m

10. And… in case you are still not impressed… If you had a mole of pennies you would indeed be rich. Let’s say you wanted to buy kite string at the outrageous cost of 1 million dollars per inch… you would get your money's worth.

11. In fact, after stretching your string around the Earth one million times, and to the Moon and back twenty-five times, you could take the string you have left over and sell it back at only one penny an inch.

12. And this would get you enough money to buy every man, woman and child in the US a $5000 motorcycle and enough gasoline to run it non-stop at 55 mph for a year!!

13. And… after those purchases, you would still have enough money left over to give every man, woman, and child in the whole world $4365!!! (WOW)

14. But what is so special about the number: 6.02 x 1023? It relates back to the unit “amu.” Recall that “amu” stands for “atomic mass unit.” 1 amu is roughly the mass of a proton (or a neutron).

15. But exactly how big is an “amu?” And how does it relate to the mass unit we are more familiar with – the gram? That’s where 6.02 x 1023 comes in: 6.02 x 1023 amu = 1 g.

16. Still, why is that such a special number that it gets its own name? 2.54 cm = 1 in, but there is no special name given to “2.54.” The special thing about the mole (6.02 x 1023) is that it provides a simple way for us to “count out” atoms and molecules by weighing them.

17. That’s so important, it’s worth repeating: The mole provides a simple way for us to “count out” atoms and molecules by weighing them.

18. 29 Cu 63.55 To understand how this works, let’s take a look at the periodic table: Take Cu for example We can see that the average mass for a Cu atom is 63.55 amu. 29 Cu 63.55

19. 29 Cu 63.55 1 g 6.02 x 1023 amu = 63.55 g (6.02 x 1023)x(63.55 amu) X So how much would a mole of Cu weigh? Well, if one atom of Cu weighs 63.55 amu, then one mole of Cu (that’s 6.02x1023 atoms of Cu) should weigh:(6.02 x 1023)x(63.55 amu). And what would that be in grams? Let’s use factor label: Now watch how this simplifies: And so do the 6.02 x 1023’s… First, the amu’s cancel… What does that leave us with…? That means we didn’t really have to do any calculation at all: The mass of one mole of Cu is simply Cu’s atomic mass expressed in grams.

20. 10 Ne 20.18 And does this neat little trick work for every element in the table? Let’s try neon. We can see that the average mass for a neon atom is 20.18 amu. 10 Ne 20.18

21. 10 Ne 20.18 1 g 6.02 x 1023 amu = 20.18 g (6.02 x 1023)x(20.18 amu) X So how much would a mole of Ne weigh? If one atom of Ne weighs 20.18 amu, then one mole of Ne (that’s 6.02x1023 atoms of Ne) should weigh:(6.02 x 1023)x(20.18 amu). And what would that be in grams? Let’s use factor label: Again, watch how this simplifies: And so do the 6.02 x 1023’s… First, the amu’s cancel… What does that leave us with…? So the “20.18” tells us two things about neon. First, it tells us that one atom of Ne weighs 20.18 amus. Second, it tells us that one mole of Ne weighs 20.18 grams. How convenient is that!

22. So now, take out a periodic table and try answering the following questions. As you figure out the answers, record them on the mole tutorial work sheet.

23. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 1. How much would one mole of He weigh?

24. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 1. How much would one mole of He weigh? Sorry, try again

25. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 1. How much would one mole of He weigh? Sorry, try again

26. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms CORRECT! 1. How much would one mole of He weigh? One mole of He would weigh 4.0026 g Write that answer on your worksheet, and then try the next question.

27. 1 amu 4.0026 amu 2 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 2. How much would one atom of He weigh?

28. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 2. How much would one atom of He weigh? Sorry, try again

29. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 2. How much would one atom of He weigh? Sorry, try again

30. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms CORRECT! 2. How much would one atom of He weigh? One atom of He would weigh 4.0026 amu. Write that answer on your worksheet, and then try the next question.

31. 1 amu 40.08 amu 12 amu 6.02x1023 amu 1 g 12 g 40.08 g 6.02x1023 g 1 atom 12 atoms 40.08 atoms 6.02x1023 atoms 3. How much would one atom of Ca weigh?

32. 1 amu 12 amu 40.08 amu 6.02x1023 amu 1 g 12 g 40.08 g 6.02x1023 g 1 atom 12 atoms 40.08 atoms 6.02x1023 atoms 3. How much would one atom of Ca weigh? Sorry, try again

33. 1 amu 12 amu 40.08 amu 6.02x1023 amu 1 g 12 g 40.08 g 6.02x1023 g 1 atom 12 atoms 40.08 atoms 6.02x1023 atoms 3. How much would one atom of Ca weigh? Sorry, try again

34. 1 amu 12 amu 40.08 amu 6.02x1023 amu 1 g 12 g 40.08 g 6.02x1023 g 1 atom 12 atoms 40.08 atoms 6.02x1023 atoms CORRECT! 3. How much would one atom of Ca weigh? One atom of Ca would weigh 40.08 amu. Write that answer on your worksheet, and then try the next question.

35. 1 amu 40.08 amu 12 amu 6.02x1023 amu 1 g 12 g 40.08 g 6.02x1023 g 1 atom 12 atoms 40.08 atoms 6.02x1023 atoms 4. How much would one mole of Ca weigh?

36. 1 amu 12 amu 40.08 amu 6.02x1023 amu 1 g 12 g 40.08 g 6.02x1023 g 1 atom 12 atoms 40.08 atoms 6.02x1023 atoms 4. How much would one mole of Ca weigh? Sorry, try again

37. 1 amu 12 amu 40.08 amu 6.02x1023 amu 1 g 12 g 40.08 g 6.02x1023 g 1 atom 12 atoms 40.08 atoms 6.02x1023 atoms 4. How much would one mole of Ca weigh? Sorry, try again

38. 1 amu 12 amu 40.08 amu 6.02x1023 amu 1 g 12 g 40.08 g 6.02x1023 g 1 atom 12 atoms 40.08 atoms 6.02x1023 atoms CORRECT! 4. How much would one mole of Ca weigh? One mole of Ca would weigh 40.08 g. Write that answer on your worksheet, and then try the next question.

39. 1 amu 4.0026 amu 2 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 5. How many atoms would be present in one mole of He?

40. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 5. How many atoms would be present in one mole of He? Sorry, try again

41. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 5. How many atoms would be present in one mole of He? Sorry, try again

42. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms CORRECT! 5. How many atoms would be present in one mole of He weigh? In one mole of He there would be 6.02x1023 atoms present. Write that answer on your worksheet, and then try the next question.

43. 1 amu 4.0026 amu 2 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 6. How many atoms would be present in one mole of Ca?

44. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 6. How many atoms would be present in one mole of Ca? Sorry, try again

45. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms 6. How many atoms would be present in one mole of Ca? Sorry, try again

46. 1 amu 2 amu 4.0026 amu 6.02x1023 amu 1 g 2 g 4.0026 g 6.02x1023 g 1 atom 2 atoms 4.0026 atoms 6.02x1023 atoms CORRECT! 6. How many atoms would be present in one mole of Ca? In one mole of Ca there would be 6.02x1023 atoms present. Write that answer on your worksheet, and now let’s return to the tutorial.

47. So what have we learned so far? 1) One atom of any element weighs its atomic mass in amu’s. (thus one atom of C weighs 12.011 amu) 2) One mole of any element weighs its atomic mass in grams. (thus one mole of C weighs 12.011 g) 3) One mole of any element contains 6.02 x 1023 atoms. (thus one mole of C contains 6.02 x 1023 atoms)

48. But what about compounds like water (H2O), carbon dioxide (CO2) and propane (C3H8)… Does the mole apply to them too? C C C C C C C C C C C C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O ABSOLUTELY! But there is a difference… When we talk about 1 mole of an element like C, we are talking about 6.02x1023atoms of C… That’s 6.02x1023 of these: But when we talk about 1 mole of a compound like H2O, for example, we are talking about 6.02x1023molecules of H2O… That’s 6.02x1023 of these:

49. To figure out how much a single molecule of water weighs, you would simply look at its chemical formula: H2O. That’s two atoms of H and one atom of O. So the total mass would just be 2(1.0 amu) + 1(16.0 amu) = 18.0 amu. So if a molecule of water weighs 18.0 amu, how much would one mole of water weigh? If you were thinking 18.0 g, then good job! How much would one molecule of CF4 weigh? That’s one C and four F’s: 1(12.0 amu) + 4(19.0 amu) = 88.0 amu And one moleof CF4 would weigh 88.0 g

50. Again, using a periodic table (and perhaps a calculator if you need one), try answering the following questions? As you figure out the answers, record them on the mole tutorial work sheet.