1. OB: Intro to the Mole You gotta have a reference table and a calculator of your own now. No exceptions.

2. One way to measure how much someone loves you is to see if they know that a dozen roses means twelve.* (*not really, it’s a silly comparison) A deck of cards means 52 cards. 51 is not a deck. And we know shoes come in pairs of 2.

3. You could have a pair of atoms, or a dozen, or even 52, but you wouldn’t know it because atoms are so small. We need a bigger unit, and that’s what a mole is. 1. A mole is a certain number of particles. You could have a mole of: atoms molecules cations or anions formula units (!) these are the smallest mathematical part of an ionic compound since “molecules” of a salt do not exist naturally ever. 2. A mole is 6.02 x 10 23 of something. That is: 602,000,000,000,000,000,000,000 of them. That is a really, really big number.

4. No one ever counted that many, it’s been worked out mathematically and is called: 3. Avogadro’s Number is 6.02 x 10 23 in honor of Amedo Avogadro, an Italian chemist who studied gases. 4. So, how many atoms are in one mole of mercury? That would be 6.02 x 10 23 atoms of mercury. 5. How many atoms are in one half mole of carbon? That’s just 3.01 x 10 23 atoms of carbon. half

5. What is the mass of one mole of mercury? 6. One atom of Hg has a weighted average mass of 200.59 amu 7. In our class we’d round that to the nearest whole number, so 201 amu is the mass of one atom of mercury. 8. 6.02 x 10 23 atoms of mercury has mass of 201 grams. Did you catch that conversion factor?

6. 9. Determine the mass of… 1.0 mole of carbon = 2.0 moles of aluminum 3.0 moles of helium 0.50 moles magnesium This one will be tricky, tricky, tricky… 10. What’s the mass of 1.0 mole of oxygen gas?

7. 9. Determine the mass of… 1.0 mole of carbon 12 grams 2.0 moles of Al 2 x 27g = 54 grams 3.0 moles of He 3 x 4g = 12 grams 0.50 moles Mg 0.50 x 24g = 24 grams This one will be tricky, tricky, tricky… 10. What’s the mass of 1.0 mole of oxygen gas? 1 x (2 x 16g) = 32 g

8. 11. The HONClBrIF Twins need special attention. They exist in nature, when PURE, as diatomic molecules, not individual atoms. So, their MOLAR MASS, the mass of one mole of a substance is as follows… H 2 2 x 1g = 2g/mole O 2 2 x 16 g = 32 g/mole N 2 2 x 14g = 28 g/mole Cl 2 2 x 35g = 70 g/mole Br 2 2 x 80g = 160 g/mole I 2 2 x 127g = 254 g/mole F 2 2 x 19g = 38 g/mole Always round atomic mass to nearest WHOLE NUMBER! Mass of fluorine is 18.9984 so it rounds to 19

9. 12. What is the mass of one mole of magnesium oxide? (wow, this is a great question! 12b. I could also have asked, what is the molar mass of magnesium oxide? (means the same thing) 14. One mole of a substance is equal to it’s molar mass. That’s vocabulary. To do this, write the formula, underline it, and list the atoms in the compound like this: MgO Mg O

10. MgO Mg = 1 mole x 24 g = 24 g O = 1 mole x 16 g = 16 g 40 g/mole You can say it this way: 15. MgO has a molar mass of 40 grams/mole Or There are 40 grams of MgO = one mole of MgO.

11. MgO Mg = 1 mole x 24 g = 24 g O = 1 mole x 16 g = 16 g 40 g/mole 16. VERY IMPORTANT NOTE: In a compound, like magnesium oxide, oxygen is NOT PURE, it’s bonded to the magnesium. It it NOT PURE OXYGEN, it’s not a HONClBrIF Twin here. Those 7 elements are diatomic when PURE. When they bond to other atoms in compounds, they are not diatomic. Another example is H 2 O, with one oxygen!

12. 17. Determine the molar mass of carbon dioxide CO 2 C O

13. This slide intentionally left blank. Do not worry about this, it has nothing specifically to do with you.

14. 17. Determine the molar mass of carbon dioxide CO 2 C 1 x 12 g = 12 g O 2 x 16 g = 32 g CO 2 is 44 g/mole

15. 18. What is the mass of 2.70 moles of sulfur? (do below first) To do these problems we need first to determine the molar mass for the element… 19. The molar mass of sulfur is: ________________________ 20. Which means, one mole sulfur = _______ grams of sulfur (that EQUALITY is a conversion factor begging to be used, with unlimited SF) Go back to question 18 now…

16. The molar mass of sulfur is 32g/mole. To do this math problem: 2.70 moles S 1 x 32 g Sulfur 1 mole sulfur = 86.4 g S Starting point of the problem over one Conversion factor from periodic table with unlimited SF Correct answer with proper number of SF (3) In every box on the periodic table is a conversion factor waiting for you. One mole of atoms of any element is equal to the molar mass (with unlimited SF)

17. 21. What is the mass of 0.356 moles of lead? First determine the molar mass of lead and write it down neatly. Then, start the problem in the right place, put it “over one”. (it’s always best to start at the beginning). Then, neatly write out the math, use your calculators, get it right the first time. 21b. What’s her name? She’s one of my heroes!

18. 0.356 moles lead 1 x 207 g lead 1 mole Pb =73.692 grams 73.7 g Pb (3SF) It is way cool that you can do this now… Try one more: 22. What is the mass of 6.15 moles of boron? Boron has a molar mass of 11 g/mole That number has unlimited SF, since one mole boron = 11 grams of boron 21.

19. 6.15 mole B 1 X 11 g B 1 mole B = 67.65 g B 67.6 g Boron (3 SF) Tonight’s Homework Play whack a mole in your head. Do the QUIZ (no points, but are you ready for your UNIT CELEBRATION OF KNOWLEDGE? When is the 1 st Quarter Unit Celebration of Knowledge – check Arbuiso.com 22.

20. OB: Mole class #2 Calculating Molar Masses, and numbers of atoms in any mass of an element or compound Periodic tables and calculators mandatory right now

21. What is molar mass? How do we calculate it? What does it mean? What’s the name for this compound? 23. Al(MnO 4 ) 3 __________________________ 24. How do we calculate the mass of 1 mole of it? (sum of the parts) Al(MnO 4 ) 3 Al Mn O

22. What is molar mass? How do we calculate it? What does it mean? What’s the name for this compound? 23. Al(MnO 4 ) 3 Aluminum Permanganate 24. How do we calculate the mass of 1 mole of it? (sum of the parts) Al(MnO 4 ) 3 Al 1 x 27 g = 27 g Mn 3 x 55 g = 165 g O 12 x 16 g = 192 g 384 g/mole

23. 25A and B. NYS Regents likes vocabulary. They like to use extra words like… A. Gram Molecular Mass - means molar mass for a molecular compound which forms into molecules Or B. Gram Formula Mass - means molar mass for an ionic compound that makes formula units Both of these mean molar mass. Molar mass is the number of grams in 1 mole of a substance. It’s just extra vocabulary, so don’t be fooled.

24. 26. What’s the gram molecular mass of SULFUR TRIOXIDE? so 3

25. 26. What’s the gram molecular mass of SULFUR TRIOXIDE? SO 3 S 1 mole x 32 g = 32 g O 3 moles x 16 g = 48 g 80 g/mole The molar mass of sulfur trioxide is 80 grams Or, if you have 80 grams of SO 3, you have 1 mole of SO 3 Or, 80 grams of SO 3 = 6.02 x 10 23 molecules of SO 3

26. 27. Calculate the gram formula mass (molar mass) of sodium sulfate. (write formula correctly first) __________________________

27. 27. sodium sulfate. Na 2 SO 4 Na 2 moles x 23 g = 46 g S 1 mole x 32 g = 32 g O 4 moles x 16 g = 64 g 142 g/mole

28. Using the concept of moles and molar mass, you can determine how many moles are present in a given mass of a substance. 28. Example If you have 103.2 g of Nickel, how many moles do you have? 103.2 g Ni 1 Start at the beginning (please use units)

29. 28. Using the concept of moles and molar mass, you can determine how many moles are present in a given mass of a substance. For example If you have 103.2 g of Nickel, how many moles do you have? 103.2 g Ni 1 x 1 mole Ni 59 g Ni =1.749 moles of Nickel 4 SFUnlimited SFNeeds 4 SF too

30. 29. 551 grams of gold is how many moles of gold?

31. 551 g Au 1 x 1 mole Au 197 g Au = 2.80 moles Au

32. 30. 37.33 g of silicon is how many moles of silicon?

33. 37.33 g Si 1 x 1 mole Si 28 g Si = 1.333 moles Si (4 SF) Unlimited SF in this equality All molar masses have unlimited SF

34. Remember 6.02 x 10 23 particles = 1 mole of anything 31. How many moles of zinc are in 1.25 x 10 23 atoms?

35. 31. How many moles of Zn are in 1.25 x 10 23 atoms? 1.25 x 10 23 atoms Zn 1 x 1 mole Zn 6.02 x 10 23 atoms Zn = 1.25 6.02 x 10 23 = 0.208 moles zinc (3 SF) This expression = 1

36. 32. How many moles of xenon gas are in 8.75 x 10 24 atoms of Xe?

37. 32. How many moles of Xe gas are in 5.75 x 10 24 atoms of Xe? 8.75 x 10 24 atoms of Xe 1 x 1 mole Xe 6.02 x 10 23 atoms of Xe = 8.75 6.02 x 10 24 10 23 moles Xe = 1.45 x 10 1 moles Xe = 14.5 moles Xe

38. Last slide o’ the day #33 If you find 50.0 grams of pure silver, how many atoms of silver did you find? A hint might be required, this is a 2-step problem, first convert grams → moles, then Convert moles → atoms

39. 50.0 g Ag 1 1 mole Ag 108 g Ag = 0.463 moles Ag X 0.463 mole Ag 1 6.02 x 10 23 atoms Ag 1 mole Ag X = 0.463 x 6.02 x 10 23 atoms Ag = 2.79 x 10 23 atoms of silver 3SF 33.

40. 33. Or, do it all in one bigger math computation – in a multistep dimensional analysis: 50.0 g Ag 1 1 mole Ag 108 g Ag X X 6.02 x 10 23 atoms Ag 1 mole Ag = 2.79 x 10 23 atoms of silver (3SF) (50.0 X 1 X 6.02) X (10 23 atoms Ag) 1 X 108 X 1 301 108 ( ) (10 23 atoms Ag) =

41. OBJECTIVE: Moles Class #3 Students will grasp the concept of moles being central to mass, to numbers of particles, and to gas volume. They will practice 2-step dimensional analysis conversion problems. Periodic tables and calculators now. Lots of paper please. Get ready to draw a shark

42. 34. The mole in chemistry has many connections. One mole = 6.02 x 10 23 particles (atoms, molecules, FU’s, etc.) One mole = the molar mass of an element One mole = the molar mass of a compound Now… 35. 1 mole of any gas = 22.4 liters of gas* *the gas must be at what’s called standard temperature + standard pressure which is on table A. That’s 273 Kelvin or 0 °C and one atmosphere of pressure AKA: STP

43. Moles connect mass to volume to numbers of particles. It’s like a universal math tool that you can use to make amazing connections. On the next page you will draw a cool map, please use at least one half a page and be neat. Copy everything especially the mole shark…

44. Mole Island Chemistry Vacationland

45. Mole Island Volume Island Particle Island Mass Island 1 mole = 22.4 L of gas 1 mole = 6.02 x 10 23 particles 1 mole = molar mass

46. Stay on the islands or use the bridges only. Pay the toll in both directions. If you try to take a shortcut, the Mole Shark will eat you. The biggest mole problem is only 2 steps. Always use units. 37. How many liters of helium gas are in 65.3 g of helium? (hint: start at the beginning)

47. Mole Island Volume Island Particle Island Mass Island 65.3 g He 1 mole = 22.4 L of gas 1 mole = 6.02 x 10 23 particles 1 mole = molar mass STEP ONE STEP TWO Figure out where you are starting, and where you want to go, stay on the bridges! No Shark Problems.

48. 65.3 g He 1 37. How many liters of He gas are in 65.3 grams of helium?

49. Using the map, start at mass island, go to mole island, then go on to volume island. 65.3 g He 1 1 mole He 4 g He x = 16.3 moles He 16.3 moles He 1 x 22.4 L He 1 mole He = 365 liters He This is a 2 step problem, watch SF, go slow, use your units always.

50. Problem 38: If you find exactly 3.58 x 10 24 atoms of aluminum, how many grams do you have? This is another 2 step problem. Start at particle island, to moles, then a trip to mass island. Look at map now.

51. Problem 38: If you find exactly 3.58 x 10 24 atoms of aluminum, how many grams do you have? 3.58 x 10 24 atoms Al 1 x 1 mole Al 6.02 x 10 23 atoms Al = 3.58 6.02 x 10 24 10 23 = 0.595 x 10 1 moles Al 5.95 moles Al one more step!

52. 5.95 moles Al 1 x 27 g Al 1 mole Al = 161 g Al (3 SF) The mole island map will be your handy guide through all mole problems. No problems exist that can’t be figured out with the map. Always use units, always write big enough to cancel out, always go slowly, and you cannot go wrong. Draw this map NEATLY below table H, but ONLY ON THE RIGHT SIDE NO line up and down, just stay to the left please – save the right side for next month.

53. 39. Last problem for now: You are re-gifted a present from your weird Uncle Al. He gives you a canister that says it contains exactly 7.99 x 10 22 molecules of nitrogen gas. What is the mass of this gas? (remember HONClBrIF twins!)

54. 7.99 x 10 22 molecules N 2 1 X 39. 7.99 x 10 22 molecules of nitrogen gas. What is the mass of this gas?

55. 7.99 x 10 22 molecules N 2 1 x 1 mole N 2 6.02 x 10 23 molecules N 2 = 7.99 6.02 x 10 22 10 23 = 1.33 x 10 -1 moles N 2 1.33 x 10 -1 moles N 2 = 0.133 moles N 2 0.133 moles N 2 1 x 28 g N 2 1 mole N 2 = 3.72 g N 2 gas 39.

56. Mole Island Volume Island Particle Island Mass Island 1 mole = 22.4 L of gas 1 mole = 6.02 x 10 23 particles 1 mole = molar mass CLOSURE: Don’t do this problem, show me with your fingers what island we start on, and where we’re going! What is the mass in grams of a balloon of carbon dioxide that is 5.75 Liters big? 1 2 3

57. Mole Island Volume Island Particle Island Mass Island 1 mole = 22.4 L of gas 1 mole = 6.02 x 10 23 particles 1 mole = molar mass CLOSURE: Don’t do this problem, show me with your fingers what island we start on, and where we’re going! What is the mass in grams of a balloon of carbon dioxide that is 5.75 Liters big? 1 2 3

58. Next time, we’ll do the Mole Lab. Come on time, come with a calculator and a smile. Homework tonight… Start reading the Mole BASICS. That means take some notes, write down some questions to bring into class. Peace, love and chemistry.

59. OB: introduction to the idea of percent composition by mass You will need a calculator and periodic table.

60. There is nothing like a good fruit dessert on a sad day. Or a happy day. I especially love bananas. And blueberries and strawberries. This dessert has half strawberries, and one quarter blueberries and one quarter bananas as a topping. I’d prefer more bananas, but google images limited me. Now let’s do some math. Recipe: (a tart with cream plus) 6 ounces strawberries, 3 ounces blueberries 3 ounces of bananas.

61. Recipe: 6 oz. strawberries, 3 oz. blueberries + 3 oz. bananas. For my dessert with 12 ounces of fruit (to offset the calories from sugar) you could easily say it’s 50% strawberries, and it’s 25% bananas, and it’s also 25% blueberries. These percents are easily determined by dividing the mass of the fruit by the total mass of all the fruit (like this) 6 oz. strawberries 12 oz fruit topping X 100% = 50% strawberries by mass 3 oz. bananas 12 oz. fruit topping X 100% = 25% bananas by mass

62. 40. How do we determine the percent composition by mass of hydrogen and oxygen in water? First we must determine the molar mass (on the left), then… H2OH2O HO HO

63. 40. How do we determine the percent composition by mass of hydrogen and oxygen in water? First we must determine the molar mass (on the left), then… H 2 O % Comp by Mass H 2 x 1 = 2 g O 1 x 16 = 16 g 18 g/mole

64. 40. How do we determine the percent composition by mass of hydrogen and oxygen in water? First we must determine the molar mass, then… H 2 O % Comp by Mass H 2 x 1 = 2 g O 1 x 16 = 16 g 18 g/mole 2 g 18 g H X 100% = 11% O X 100% = 89% 16 g 18 g

65. 40. How do we determine the percent composition by mass of hydrogen and oxygen in water? First we must determine the molar mass, then… H 2 O % Comp by Mass H 2 x 1 = 2 g O 1 x 16 = 16 g 18 g/mole 2 g 18 g H X 100% = 11% O X 100% = 89% 16 g 18 g 100% OR DARN CLOSE TO IT!

66. 41. What’s the percent composition by mass of sodium and chlorine in sodium chloride? First do the molar mass on the left, then the % comp by mass on the right. NaCl

67. 41. What’s the percent composition by mass of sodium and chlorine in NaCl? Next, do the % comp on the right side NaCl Na 1 x 23g = 23g Cl 1 x 35g = 35 g 58 g/mole

68. 41. What’s the percent composition by mass of sodium and chlorine in NaCl? Fabulous! NaCl Na 1 x 23g = 23g Cl 1 x 35g = 35 g 58 g/mole Na Cl 23g 58 g 35g 58 g X 100% = 39.6% X 100% = 60.3% Are we ok with 99.9% or not?

69. 42. What’s the percent composition by mass for Copper (II) sulfate? CuSO 4 Cu 1 x S 1 x O 4 x

70. 42. What’s the percent composition by mass for Copper (II) sulfate? Now, do the % comp on the right side of the page… CuSO 4 Cu 1 x 64 = 64 S 1 x 32 = 32 O 4 x 16 = 64 160 g/mole

71. 42. What’s the percent composition by mass for Copper (II) sulfate? Are you getting this yet? CuSO 4 Cu 1 x 64 = 64 Cu S 1 x 32 = 32 S O 4 x 16 = 64 O 160 g/mole 64 g 160 g 32 g 160 g 64 g 160 g X 100% = 40% X 100% = 20% 100%

72. This means that the compound CuSO 4 is 40% copper by mass, also 40% oxygen by mass, and only 20% sulfur by mass. 43. So, imagine that you have a pocketful of this copper (II) sulfate, say, 456 grams. That’s just more than a pound. How many grams of your pocketful of crystals is just copper? Or oxygen? Or sulfur?

73. 43. 456 g x 0.40 copper = 182.4 g copper by mass 456 g x 0.40 oxygen = 182.4 g oxygen by mass 456 g x 0.20 sulfur = 91.2 grams sulfur Copper (II) sulfate will ALWAYS be 40% copper, always be 40% oxygen, and always be 20% sulfur. No Matter How Much You Have.

74. Before we calculated the % comp by mass for water, it was 11% hydrogen and 89% oxygen. 44. Think now… There are 2 atoms of hydrogen for every one atom of oxygen. Why is the percent comp by mass so low for hydrogen? Shouldn’t it be higher? ________________ 45. You fill up a water balloon to 1250 mL. It’s mass is also 1250 grams. How many of those grams are just oxygen?

75. 1250 g water X 89% oxygen 1250 g water X.89 oxygen = 1112.5 g are just oxygen

76. Knowing the molar mass of a compound also will allow you to find the percent composition by mass of it as well. The formula for this is on the back page of your reference table. Let’s look at it now. % comp. by mass = the mass of the part we’re looking at the mass of the whole X 100%

77. Question 46. What is the percent composition by mass of aluminum in aluminum hydroxide? Let’s round answer to 3 SF

78. Question 46. What is the percent composition by mass of aluminum in aluminum hydroxide? Let’s round answer to 3 SF Al(OH) 3 Al 1 x 27 = 27 Al O 3 x 16 = 48 O H 3 x 1 = 3 H 78 g/mole 27g 78g X 100% = 34.6% 48g 78g X 100% = 61.5% 3g 78g X 100% = 3.85% 99.95% = 100.%

79. OB: Percent composition by mass and mole problems combined. Put all stuff on black tables. Get a pen, calculator, reference tables, and NOTES (start #47)

80. 47. You find a box with a bar of metal that has stamped into it PURE GOLD. The bar weighs 500. grams EXACTLY. How many atoms of gold do you have?

81. 500. g Au 1 x 1 mole Au 197 g Au =2.54 moles Au 2.54 moles Au 1 x 6.02 x 10 23 atoms Au 1 mole Au = 2.54 x 6.02 x 10 23 atoms Au = 15.3 x 10 23 = 1.53 x 10 24 atoms Au

82. 48. If you have 50.0 g of sodium hydroxide, how many grams of those are oxygen?

83. NaOH % Comp by Mass Na 1x23= 23 O 1x16= 16 O H 1x1 = 1 40g/mole 16g 40g X 100% = 40% 50.0 g x.40 = 20.0 grams oxygen

84. 346 L neon gas Assume STP 49. Calculate the mass of the neon in the balloon.

85. 346 L neon gas Assume STP 346 L Ne 1 x 1 mole Ne 22.4 L Ne = 15.4 moles Neon 15.4 moles Ne 1 x 20 g Ne 1 mole Ne = 308 g Ne 49. Calculate the mass of the neon in the balloon.

86. 50. Empirical Formulas are not “real” chemistry, but an incursion of mathematical ratios into chemical formulas. They look like chemical formulas, but really they are JUST MATH RATIOS, And seem to be specifically designed to FOOL YOU. Don’t get mad, just learn this simple technique, and roll with them.

87. 50. For example Glucose formula is C 6 H 12 O 6 which has a 6:12:6 atomic ratio John Dalton said “simple, whole number ratios” for compounds, but this one exists and he didn’t know that. SOME organic compounds that are BIG do not follow his rules. It’s can be mathematically reduced to a 1:2:1 ratio This can exist on paper, in math, but not in real chemistry. These “reduced” to simplest ratio formulas are called 51. The empirical formula of C 6 H 12 O 6 is CH 2 O

88. EMPIRICAL FORMULAS They’re math, not chemistry. Most empirical formulas can’t even bond together, and even if they do, they are NOT the same compound just because they share a ratio with something else. 52. CH 2 O does not exist as a compound. It’s MATH that “looks” like chemistry.

89. 53. Let’s practice empirical formulas now C 6 H 12 O 6 (glucose) C 8 H 18 (octane) C 24 H 48 (candle wax) C 2 H 2 (acetylene gas) H 2 O 2 (hydrogen peroxide) C 6 H 6 (cyclohexene) C 10 H 22 (decane) C 6 H 14 (hexane) C 5 H 10 O 5 (pentose) Empirical formulas are mathematical ratios of atoms to atoms in compounds, written (CONFUSINGLY) as chemical formulas

90. 53. Let’s practice empirical formulas now C 6 H 12 O 6 C 8 H 18 (octane) C 24 H 48 (candle wax) C 2 H 2 (acetylene gas) H 2 O 2 (hydrogen peroxide) C 6 H 6 (cyclohexene) C 10 H 22 (decane) C 6 H 14 (hexane) C 5 H 10 O 5 (pentose) CH 2 O C 4 H 9 CH 2 CH HO CH C 5 H 11 C 3 H 7 CH 2 O

91. 54. If you find 11.200 moles of gold and gold is selling for about $40.39/gram, are you rich or just happy, or does it not matter all that much? (hint, how many grams are in that many moles?

92. 54. If you find 11.2 moles of gold and gold is selling for about $40.39/gram, are you rich or just happy, or does it not matter all that much? 11.200 moles Au 1 x 197 g Au 1 mole Au = 2206.4 g Au 3SF 2206.4 g Au 1 x _$40.39_ 1 g Au = $89,116 (wow)

93. Tell the STEPS of how to do this: You have 654 grams of CO 2(G) at STP. What size balloon do you need to carry it in? What is STP?

94. Tell the STEPS of how to do this: You have 654 grams of CO 2(G) at STP. What size balloon do you need to carry it in? What is STP? STP is standard temp and pressure from table A on reference tables. Convert mass to moles with the 44g/mole molar mass of CO 2. Then convert moles to liters with 1 mole = 22.4 liters of gas. Watch SF.

95. We will try something new today. 1.NO TALKING AT ALL, please respect the silence. Put phones away. 2.Take out notes, mole map, reference tables, and pen 3.Put back pack OFF of your desk 4.You will DO these problems ALONE, we will review them, I will talk, you will listen. 5.You will learn or feel the pressure of what you don’t know yet but should. 6.I hope you will feel empowered that YOU KNOW this, or SCARED ENOUGH to come in for some extra help at lunch today or tomorrow. 7.You should be able to do ALL OF THESE ALREADY. 8.Stop making believe it’s alright if it’s not.

96. OB: Practice mole problems and percent composition by mass problems. Get a calculator and reference table, mole island maps will help. In 35 minutes you will own mole problems, molar mass, and percent comp by mass, or else you will come in to see me for extra help. There is no in between on this. Own it today.

97. 55. Convert 4.87 x 10 24 formula units of sodium chloride to grams. (look at map)

98. 55. Convert 4.87 x 10 24 formula units of sodium chloride to grams. 4.87 x 10 24 FU NaCl 1 x 1 mole NaCl 6.02 x 10 23 FU NaCl = 4.87 6.02 x 10 24 10 23 = 0.809 x 10 1 = 8.09 moles NaCl 8.09 moles NaCl 1 x 58 g NaCl 1 mole NaCl = 469 grams NaCl

99. 56. You have 125 grams of carbon dioxide gas in a balloon at STP. What is its volume in liters?

100. 125 g CO 2 1 x 1 mole CO 2 44 g CO 2 = 2.84 moles CO 2 2.84 moles CO 2 1 x 22.4 L CO 2 1 mole CO 2 = 63.6 Liters CO 2

101. 57. If you happen to have 888 g of copper (II) sulfate, how many FU’s do you have?

102. 888 g CuSO 4 1 x 1 mole CuSO 4 160 g CuSO 4 = 5.55 moles CuSO 4 5.55 moles CuSO 4 1 x 6.02 x 10 23 FU CuSO 4 1 mole CuSO 4 (5.55 x 6.02) x 10 23 FU = 33.4 x 10 23 = 3.34 x 10 24 FU’s CuSO 4

103. 58. You have 67.2 g of water, how many of those grams are just hydrogen? (Round to whole number %)

104. 58. You have 67.2 g of water, how many of those grams are just hydrogen? H 2 O H 2 x 1 = 2 H O 1 x 16 = 16 O 18 g/mole 2g 18g X 100 % = 11% 16g 18g X 100 % = 89% 67.2 g x.11 = 7.39 grams just hydrogen

105. 59. What is the percent composition by mass of nickel in the compound nickel (II) carbonate?

106. NiCO 3 Ni 1x59= 59 Ni C 1x12= 12 C O 3x16= 48 O 119 g/mole 59g 119g X 100% = 49.6% 12g 119g X 100% = 10.1% 48g 119g X 100% = 40.3% 100% The answer is in the red oval, but YOU should do all the math to make sure it adds to 100%. A silly boo boo would go overlooked unless you CHECK your work

107. 60. What are the empirical formulas for the following compounds? Paraffin wax C 26 H 52 Ethene C 2 H 4 Decene C 10 H 20 Sucrose C 12 H 22 O 11 Heptane C 7 H 16 Hydrogen monochloride HCl Potassium sulfite (formula?) Cobalt (II) phosphate (formula?)

108. 60. What are the empirical formulas for the following compounds? Paraffin wax C 26 H 52 CH 2 Ethene C 2 H 4 CH 2 Decene C 10 H 20 CH 2 Sucrose C 12 H 22 O 11 C 12 H 22 O 11 Heptane C 7 H 16 C 7 H 16 Hydrogen monochloride HCl HCl Potassium sulfite K 2 SO 3 Cobalt (II) phosphate Co 3 (PO 4 ) 2 This cannot be reduced any more

109. 61. How many electrons in a Mg +2 cation? Many will choose 12 e ― Let’s practice a few of these. 62. How many electrons in the following species? Al +3 _____ Co +2 _____ Pb +4 ________ Na +1 ____ F -1 _____ S -2 ______ N -3 _____ Au +1 ______ Cu _______

110. 61. How many electrons in a Mg +2 cation? 10e ― 62. How many electrons in the following species? Al +3 10 Co +2 25 Pb +4 78 Na +1 10 F -1 10 S -2 18 N -3 8 Au +1 78 Cu 29

111. If I were you, I would RE-DO these questions AGAIN tonight and check your work. Studying means DOING work, not glancing over your notes. Do you want success? Then do it. You mole lab is due NOW. Monday you lose 5 points. On Tuesday I want the Gum Lab. On Wednesday I will want the CuSO 4 Lab that we’ll do tomorrow. Let’s go. Fix all zeros ASAP. The hard work starts today, before it truly is too late. Chemistry is golden. Chemistry is good. Not everyone’s getting it, but everybody should.

112. OB: CuSO 4 ·5H 2 O Lab and some practice at % Comp by mass problems. Take out your lab report, done or undone, a calculator, pen or pencil, and reference tables.

113. CuSO 4 ·5H 2 O Cu 1 x 64 g = 64g S 1 x 32 g = 32 g O 4 x 16 g = 64 g H 2 O 5 x 18 g = 90 g H 2 O 250 g/mole 90 g 250 g X 100% = 36% This means that no matter how much of this stuff you have, 36% by mass is water.

114. The questions… 1.It’s already done, just read it, then state it: The molar mass of CuSO 4 ·5H 2 O is 250 g/mole. The percent comp by mass of water in this hydrated crystal is 36%. 2.This is your MEASURED percent comp by mass of water in this compound, not the actual from question one, but what you measured in the lab. To do this, you need to calculate the missing mass from the compound after heating, The mass of the crucible and the hydrate minus the crucible and the anhydrous salt. That’s the mass of the missing water. This is supposed to match the 36% by mass in the actual value. It’s probably close. Then do your percent error, your measured percent comp that’s water minus 36%, equals, divided by 36%, equals, times 100%, equals. A positive or negative answer with a % unit is required.

115. 3.One mole of this good stuff is 250 g/mole. Six grams must be six times that, and it is. 6 moles x 250 g/mole = 1500 grams. 4. Here’s the tricky question. A long time ago, nearly a month and a half, I taught you how to measure the mass of atoms using the periodic table. Since atoms have protons and neutrons which have a mass of 1 amu each (in our intro class), an atom with a total number of protons and neutrons say of 23, just like sodium, would have mass of 23 amu. The atomic mass in amu is the mass of any atom. If you have a compound like water, with an oxygen and two hydrogens, that’s a total of 18 amu per molecule. If you have a big compound like CuSO 4 ·5H 2 O, then it’s a whopping 250 amu per formula unit. And if you have six formula units, that’s 6 x 250 amu = 1500 amu.

116. 5. You started with CuSO 4 ·5H 2 O, which is a hydrated (water filled) crystal ionic compound, the heating of this evaporated this water away. It changes into just CuSO 4, which is just copper (II) sulfate. This stuff is an anhydrous salt. Anhydrous means “not with water”. By sprinkling some water into this white powder it turns blue again, because it REHYDRATES. CuSO 4 ·5H 2 O in crucible CuSO 4 in crucible Evaporate water H 2 O escapes to the air ANHYDROUS SALT HYDRATED IONIC COMPOUND

117. How to write a decent conclusion First, let’s read the rubric: Conclusion - every lab report should have these 4 parts: What did you measure, what did you calculate, what is your % error, and what can you conclude or decide from this lab work? Use lots of YOUR DATA numbers, use details and less story. Work hard on this part.

118. In this lab I measured the mass of 3.00 g CuSO 4 ·5H 2 O, and the mass change as I heated it up and the water evaporated out of it. I calculated the molar mass of copper (II) sulfate pentahydrate to be 250 grams/mole, and the percent composition by mass of water in it to be 36%. From my lab data I calculated the measured percent comp by mass of water in my sample to be ____% (make sure a + or a – sign is there!). I calculated my percent error to be ___% (+/- sign here too).

119. My percent error was likely due to either small measuring errors caused by the scales, or possibly some unknown substances being present in my sample. Never admit to making any math errors to account for my percent error, since that would always be wrong. My dopey mistakes are not the reason my chemistry is not perfect, I am not allowed to make math errors in lab reports. If my error were ever, ever higher than 10% I would rush and ask my nice teacher for some advice, because no matter how crazy I might have acted in lab, even I couldn’t be that wrong in lab. Never include any of these italics in your actual lab report, the italics are for teaching purposes only.

120. To finish up, conclude something from your results. That means put it all together. For example: I can conclude from this lab that I can now determine the percent composition by mass of all compounds using the periodic table. I also know that some ionic compounds have water loosely bonded to them even in the solid phase, and that this can be measured on paper as well as in the lab. I finally can conclude that chem done on paper can be reproduced in the lab because chemistry is perfect, and I am learning how to measure well enough to prove this. I love chem, the end. When you are done, make sure all questions are answered, make sure that it’s all stapled together neatly and properly.

121. Tomorrow we will do a lab called the MgSO 4 ·7H 2 0, and that compound has two names. It’s real name is: ______________________________________________________ But you might know it as Epsom salt. It’s sold at Wegmans and other fine stores. Don’t get it into your mouth!