1. Chapter 3 & A Li’l Bit About “Moles” Chapter 3 & A Li’l Bit About “Moles” Plus some problem-solving techniques from Chapter 4. We aren’t going to do all of chapter 4, but if YOU are having difficulty with problems, I would review this chapter in detail on your own.

2. Objective A (remember, the objective refer to the Study Guides) http://www.magazine-agent.com/officials-logic-problems/magazine Look at the following numbers. How easy would it be to memorize this list and regenerate it in a week or so on a quiz? Look at the following numbers. How easy would it be to memorize this list and regenerate it in a week or so on a quiz? 1, 3, 5, 11, 21, 43, 85, 171, 341, 683, 1365, 2731, 5461, 10923, 21845 1, 3, 5, 11, 21, 43, 85, 171, 341, 683, 1365, 2731, 5461, 10923, 21845 Pretty hard? Pretty Easy? Why? Pretty hard? Pretty Easy? Why? Easy huh? OK, what’s the next number in the sequence? How about the next 5 numbers? Easy huh? OK, what’s the next number in the sequence? How about the next 5 numbers?

3. How bout this? http://shop.crackerbarrel.com/online/shopping/default.asp What if I never mentioned the list again? What if at the end of the semester…the day before the SOL…I asked you to remember those numbers? What if I never mentioned the list again? What if at the end of the semester…the day before the SOL…I asked you to remember those numbers? Could you do that? Could you do that? If so, you’re going to do really, really well when I asked you to memorize some “polyatomic ions” on page 147 of your textbook. If so, you’re going to do really, really well when I asked you to memorize some “polyatomic ions” on page 147 of your textbook. My guess is you wouldn’t remember though. My guess is you wouldn’t remember though. Cracker Barrel “Brain Teaser” Game

4. Can you make sense out of NONSENSE? ForceHourUponNeigh ForceHourUponNeigh KoranForceCisShun KoranForceCisShun HeavenFodderCount HeavenFodderCount YeBratAnent YeBratAnent SagoFarceAnew SagoFarceAnew No luck? No luck?

5. The Gettysburg Address http://www.old-picture.com/defining-moments/pictures/Abraham-Lincoln-Antietam-Battlefield.jpg http://en.wikipedia.org/wiki/Gettysburg_Address “Four score and seven years ago our fathers brought forth on this continent a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.” “Four score and seven years ago our fathers brought forth on this continent a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.” Abraham Lincoln delivered these words on Nov 19, 1863. (Go back a slide and read down instead of just left to right). Abraham Lincoln delivered these words on Nov 19, 1863. (Go back a slide and read down instead of just left to right). Being able to look at something new, and make sense of it is an important skill for the rest of this course. Being able to look at something new, and make sense of it is an important skill for the rest of this course. Yes, Ms Rackley, I know this was Antietam, but it’s a nice picture.

6. 1, 3, 5, 11, 21, 43, 85, 171, 341, 683, 1365, 2731, 5461, 10923, 21845 http://www.antiqueradiomuseum.org/RR%20Rule%20Book%20for%20CMSP&P%20RR.jpg The numbers don’t seem to follow any kind of pattern. The numbers don’t seem to follow any kind of pattern. But, what if you knew a rule? It wouldn’t just be memorization then. But, what if you knew a rule? It wouldn’t just be memorization then. OK, good point! The rule is: OK, good point! The rule is: Start with 1. Start with 1. Double and add 1. Double and add 1. Double and subtract 1. Double and subtract 1. And so on. And so on. You just wish it was that EASY!

7. Let’s look at the numbers again http://equintconsulting.com/wp-content/uploads/2008/10/istock_000005164183small.jpg 1, 3, 5, 11, 21, 43, 85, 171, 341, 683, 1365, 2731, 5461, 10923, 21845 1, 3, 5, 11, 21, 43, 85, 171, 341, 683, 1365, 2731, 5461, 10923, 21845 Start with 1. Start with 1. Double and add 1. Doubling 1 gives me 2 and adding one gives me 3. Double and add 1. Doubling 1 gives me 2 and adding one gives me 3. Double and subtract 1. Doubling 3 gives me 6 and subtracting 1 gives me 5. Double and subtract 1. Doubling 3 gives me 6 and subtracting 1 gives me 5.

8. Learn HOW to do the problem; don’t just memorize the answer! http://familyfun.go.com/Resources/printable-previews/previews/beaver_memorygame_august2.jpg Doesn’t “knowing the rule” make the list easier to memorize? Doesn’t “knowing the rule” make the list easier to memorize? You don’t have to memorize a bunch of unrelated numbers. You don’t have to memorize a bunch of unrelated numbers. IF YOU KNOW the rule, you can generate the number list on the test easily. Anytime! Anywhere! IF YOU KNOW the rule, you can generate the number list on the test easily. Anytime! Anywhere! Don’t

9. OK, does this relate to Chemistry at all? What makes Chemistry hard for most students, is you DON’T know the rule. You didn’t read the book. You didn’t look at the sample problems. You don’t know the RULE! What makes Chemistry hard for most students, is you DON’T know the rule. You didn’t read the book. You didn’t look at the sample problems. You don’t know the RULE! Every problem looks like it’s a totally brand new problem. But you’re not solving for x or y. You’re finding the “density” or some other REAL PROPERTY of matter. Every problem looks like it’s a totally brand new problem. But you’re not solving for x or y. You’re finding the “density” or some other REAL PROPERTY of matter. Every problem looks totally unrelated to anything we’ve done before. Every problem looks totally unrelated to anything we’ve done before.

10. Objective A http://www.52shows.com/wp-content/uploads/2009/02/huh.jpeg If we can understand the rules, it makes the problems much, much easier. And if you figure out how to do one problem, you should be able to figure out other problems just like it (like on the test). If we can understand the rules, it makes the problems much, much easier. And if you figure out how to do one problem, you should be able to figure out other problems just like it (like on the test). Let’s start with a simple problem. I’ll give you two numbers, and you tell me the answer. Let’s start with a simple problem. I’ll give you two numbers, and you tell me the answer. The numbers are 2 and 3. The numbers are 2 and 3. What’s the answer? What’s the answer?

11. Objective A http://www.platformnation.com/wp-content/uploads/2009/06/shrugging.jpg What are you supposed to do with those numbers? What are you supposed to do with those numbers? It’s like that in Chemistry. If you don’t have a clue, anything you do is potentially just as valid as anything else. It’s like that in Chemistry. If you don’t have a clue, anything you do is potentially just as valid as anything else. But usually it’s pretty easy to figure out what to do. But usually it’s pretty easy to figure out what to do. What?

12. Objective A http://www.tvgasm.com/newsgasm/Bill-nye.jpg In Chemistry, when we have numbers, much of the time we do one of three things: In Chemistry, when we have numbers, much of the time we do one of three things: Multiple 2 x 3 Multiple 2 x 3 Divide 2 / 3 Divide 2 / 3 Divide 3 / 2 Divide 3 / 2 If you can figure out which operation to do when, you can actually solve the problem. That’s our goal. If you can figure out which operation to do when, you can actually solve the problem. That’s our goal. What would Bill Nye do? Bill Nye is the Guy!

13. Objective A http://francisanderson.files.wordpress.com/2009/01/billy-mays.jpg We don’t use abstract or imaginary or hypothetical quantities in chemistry. We don’t use abstract or imaginary or hypothetical quantities in chemistry. We use real amounts WITH UNITS. We use real amounts WITH UNITS. 5 grams 5 grams 14.7 milliliters 14.7 milliliters 3.6 x 10 -3 moles (don’t worry about moles for a while…we’ll get to these) 3.6 x 10 -3 moles (don’t worry about moles for a while…we’ll get to these) 6.02 x 10 23 molecules 6.02 x 10 23 molecules But wait! There’s more!

14. Objective A http://www.vintagecalculators.com/html/texas_insturments_ti_58.html Notice on the last slide, most of the the numbers aren’t as nice as 2 or 3. Notice on the last slide, most of the the numbers aren’t as nice as 2 or 3. But so what. You have a calculator. Calculators don’t care how hairy the numbers are…they just add ‘em up. But so what. You have a calculator. Calculators don’t care how hairy the numbers are…they just add ‘em up. You need to get in the habit of always using units. If the units in your answer don’t work out right, the problem is WRONG. Try again. You need to get in the habit of always using units. If the units in your answer don’t work out right, the problem is WRONG. Try again. Note the cool red LED numbers Second calculator I ever got (1977). I got my first one in 1975 and all it did was add, subtract, multiply, divide AND do square roots. Quite an upgrade!

15. Units TELL you the right ANSWER! If your units don’t work out right, your answer is wrong. If your units don’t work out right, your answer is wrong. Do the problem over. Read the problem carefully before you start, and check your work when you get done. Do the problem over. Read the problem carefully before you start, and check your work when you get done. Don’t just ignore wrong units. It is a big clue for you. This is very important. Don’t just ignore wrong units. It is a big clue for you. This is very important. LISTEN to the units! LISTEN to the units!

16. Qualitative and Quantitative Data Qualitative (think quality) Qualitative (think quality) This is more a description. These are observations usually. This is more a description. These are observations usually. It’s blue. It’s hot. It’s cool. It’s smells like rotten eggs. It’s blue. It’s hot. It’s cool. It’s smells like rotten eggs. Remember to look for qualitative date when you do your lab experiments. Remember to look for qualitative date when you do your lab experiments. Quantitative (think quantity or amount) Quantitative (think quantity or amount) This is telling me how MUCH of something you have. This is telling me how MUCH of something you have. 5.0 g of baking soda. 2L of diet Coke. 4.5 moles of CO 2. 5.0 g of baking soda. 2L of diet Coke. 4.5 moles of CO 2. Remember to record quantitative data in your lab notebook when you do experiments too. Remember to record quantitative data in your lab notebook when you do experiments too.

17. Objective B Scientific notation is used to express very large and very small numbers. Scientific notation is used to express very large and very small numbers. Two very important numbers in chemistry are Two very important numbers in chemistry are 6.02 x 10 23 = 602,000,000,000,000,000,000,000 (Avogadro’s Number) 6.02 x 10 23 = 602,000,000,000,000,000,000,000 (Avogadro’s Number) 6.6 x 10 -34 = 0.00000000000000000000000000000000066 (Planck’s Constant) 6.6 x 10 -34 = 0.00000000000000000000000000000000066 (Planck’s Constant) One is a VERY LARGE number. One is a very small number. One is a VERY LARGE number. One is a very small number. Math Alert!

18. Objective B http://phoenix.fanster.com/suns/files/2009/05/pile-of-money.png 6.02 x 10 23 is very large. 6.02 x 10 23 is very large. Let’s say you had that much money. Let’s say you had that much money. $602,000,000,000,000,000,000,000.00 $602,000,000,000,000,000,000,000.00 If you spent a billion dollars every second of every day, how long do you think the money would last? If you spent a billion dollars every second of every day, how long do you think the money would last?

19. Objective B http://musikality.net/wp-content/uploads/2009/02/shocked.jpg http://hebrewandgreekreader.files.wordpress.com/2009/05/waynes_world_15b15d.jpg Answer: Answer: More than 19 million years! More than 19 million years! Way!No Way!

20. Power Point Assignment Another one for everyone…we are going to study “moles” in Chap 7. However, I want to introduce moles much earlier than that, and Chap 3 seems like a great time to do so. Another one for everyone…we are going to study “moles” in Chap 7. However, I want to introduce moles much earlier than that, and Chap 3 seems like a great time to do so. Research moles online and write a 150 word summary about moles. (Note: mole is a chemical UNIT and not a little creature that burrows into the ground.) Research moles online and write a 150 word summary about moles. (Note: mole is a chemical UNIT and not a little creature that burrows into the ground.) Be prepared for a one question quiz on Chap 3! Be prepared for a one question quiz on Chap 3!

21. Scientific Notation (we now resume our regularly scheduled power point…) We use scientific notation to more easily represent very large and/or very small numbers. We use scientific notation to more easily represent very large and/or very small numbers. We represent numbers as a “factor” times a power of 10. We represent numbers as a “factor” times a power of 10. Let’s look at 500, as an example. Let’s look at 500, as an example.

22. Scientific Notation 500 = 5 x 10 x 10, right? 500 = 5 x 10 x 10, right? But 10 x 10 = 100 and as you know, 100 = 1 x 10 2. But 10 x 10 = 100 and as you know, 100 = 1 x 10 2. So we can rewrite 500 as 5 x (1 x 10 2 ). So we can rewrite 500 as 5 x (1 x 10 2 ). But 5 x 1 just equals 5, so we usually ignore the “1” and just write 500 as 5 x 10 2. But 5 x 1 just equals 5, so we usually ignore the “1” and just write 500 as 5 x 10 2. That’s scientific notation. I’m sure this is just a review for all of you. That’s scientific notation. I’m sure this is just a review for all of you.

23. Scientific Notation How about 999? The decimal point moves from left to right. How about 999? The decimal point moves from left to right. 999 = 9.99 x 10 x 10 999 = 9.99 x 10 x 10 So, 999 = 9.99 x 10 2. So, 999 = 9.99 x 10 2. When you put a large number into scientific notation, the exponent will be positive. When you put a large number into scientific notation, the exponent will be positive.

24. Scientific Notation How about 0.0014? How about 0.0014? Well, 1.4 divided by 10 = 0.14. Well, 1.4 divided by 10 = 0.14. 0.14 divided by 10 = 0.014. 0.14 divided by 10 = 0.014. 0.014 divided by 10 = 0.0014. 0.014 divided by 10 = 0.0014. So we’re dividing by 10 and doing it 3 times. So we’re dividing by 10 and doing it 3 times.

25. Scientific Notation So 0.0014 = 1.4 ÷ 10 ÷ 10÷ 10 So 0.0014 = 1.4 ÷ 10 ÷ 10÷ 10 Or 0.0014 = 1.4 ÷ 10 3 since we are dividing by 10 three times. Or 0.0014 = 1.4 ÷ 10 3 since we are dividing by 10 three times. 1.4 = 1.4 x 10 -3 1.4 = 1.4 x 10 -3 ------- ------- 10 3 10 3

26. Scientific Notation So 0.0014 = 1.4 x 10 -3. So 0.0014 = 1.4 x 10 -3. The decimal point moved from left to right. The decimal point moved from left to right. When you put a small number into scientific notation, the exponent will be negative. When you put a small number into scientific notation, the exponent will be negative. Remember that these are exponents. Negative exponents don’t mean negative numbers, they mean very small numbers (between 0 and 1). Remember that these are exponents. Negative exponents don’t mean negative numbers, they mean very small numbers (between 0 and 1).

27. Scientific Notation 10 3 = 1,000 10 3 = 1,000 10 2 = 100 10 2 = 100 10 1 = 10 10 1 = 10 10 0 = 1 (NOT 0!!) 10 0 = 1 (NOT 0!!) 10 -1 = 0.1 10 -1 = 0.1 10 -2 = 0.01 10 -2 = 0.01 10 -3 = 0.001 10 -3 = 0.001 Go up, multiply by 10 Go down, divide by 10

28. How do we add or subtract using scientific notation? Make the exponents the same, if necessary, and then just add. Make the exponents the same, if necessary, and then just add. 5.4 x 10 3 + 2.6 x 10 2 = ? 5.4 x 10 3 + 2.6 x 10 2 = ? Let’s change the second number so that the exponents match up… Let’s change the second number so that the exponents match up… 5.4 x 10 3 + 0.26 x 10 3 = 5.66 x 10 3 5.4 x 10 3 + 0.26 x 10 3 = 5.66 x 10 3

29. How do we add or subtract using scientific notation? Does that make sense? Does that make sense? Well 5.4 x 10 3 = 5,400 Well 5.4 x 10 3 = 5,400 And 2.6 x 10 2 = 260 And 2.6 x 10 2 = 260 So 5,400 + 260 = 5,660. Putting that back in scientific notations gives us 5.66 x 10 3. So 5,400 + 260 = 5,660. Putting that back in scientific notations gives us 5.66 x 10 3. Either way, your calculator will do it for you without any problems. Maybe!! Use parentheses with scientific notation on TI-83 and TI-84 graphing calculators or you will get the wrong answer. Either way, your calculator will do it for you without any problems. Maybe!! Use parentheses with scientific notation on TI-83 and TI-84 graphing calculators or you will get the wrong answer. Math Alert!

30. How do we multiply or divide using scientific notation? Even simpler Even simpler To multiply, you multiply the numbers and add the exponents. To multiply, you multiply the numbers and add the exponents. 4 x 10 7 × 2 x 10 -3 =8 x 10 4 (80,000) 4 x 10 7 × 2 x 10 -3 =8 x 10 4 (80,000) To divide, you divide the numbers and subtract the exponents. To divide, you divide the numbers and subtract the exponents. 4 x 10 7 ÷ 2 x 10 -3 =2 x 10 10 (20,000,000,000) 4 x 10 7 ÷ 2 x 10 -3 =2 x 10 10 (20,000,000,000) × ÷

31. Sample Problems on Scientific Notation A 91.43 A 91.43 B 0.000000000154 B 0.000000000154 C 6,378,000 C 6,378,000 D 0.000008 D 0.000008 E 149,600,000,000 E 149,600,000,000 F 8934.8 F 8934.8

32. Objective c…Accuracy, Precision and Error http://www.edupics.com/en-coloring-pictures-pages-photo-dartboard-p9574.jpg Think of a dartboard. You are trying to hit the bullseye. Think of a dartboard. You are trying to hit the bullseye. Accuracy is hitting what you are aiming for. Accuracy is hitting what you are aiming for. Precision is hitting the same spot over and over. Precision is hitting the same spot over and over. Is this accurate, precise, or both, or neither?

33. Objective c…Accuracy, Precision and Error http://comps.fotosearch.com/comp/IGS/IGS170/dartboard-darts_~IS028-013.jpg Think of a dartboard. You are trying to hit the bullseye. Think of a dartboard. You are trying to hit the bullseye. If you hit the edge of the dartboard, you are not accurate. If you hit the edge of the dartboard, you are not accurate. If your darts are all over the place, you are not precise. If your darts are all over the place, you are not precise. Both accurate AND precise!

34. Objective c…Accuracy, Precision and Error http://www.durhamtech.edu/graphics/programs/univtransf/chemlab1lg.jpg In Chemistry labs, we will take measurements. In Chemistry labs, we will take measurements. Accuracy is how close you are to the TRUE value. Accuracy is how close you are to the TRUE value. Precision is how close all of your measurements are to each other. Precision is how close all of your measurements are to each other. Take your time. Know what you are doing BEFORE you do it. Pay attention to detail. No one in this group is not involved. You’ll get good results. Everyone working together safely and observing what’s happening.

35. Objective c…Accuracy, Precision and Error Can you be accurate (or have accuracy) with only 1 measurement? Can you be accurate (or have accuracy) with only 1 measurement? Can you be precise (or have precision) with only 1 measurement? Can you be precise (or have precision) with only 1 measurement? Yes, accuracy is compared to a “true” value. No, precision is “closeness” to all other measurements

36. Objective c…Accuracy, Precision and Error Student A had 3 measurements: 80, 85, 90 Average = 85.0 Student A had 3 measurements: 80, 85, 90 Average = 85.0 Student B had 3 measurements: 84.9, 85.0, 85.1 Average = 85.0 Student B had 3 measurements: 84.9, 85.0, 85.1 Average = 85.0 Student C had 3 measurements: 82.1, 82.2, 82.3Average = 82.2 Student C had 3 measurements: 82.1, 82.2, 82.3Average = 82.2 Student D had 3 measurements: 70.2, 82.2, 94.2Average = 82.2 Student D had 3 measurements: 70.2, 82.2, 94.2Average = 82.2 The accepted value = 84.9. Who is accurate? Who is precise? The accepted value = 84.9. Who is accurate? Who is precise? Accurate, Not Precise Not Accurate, Not Precise Accurate, Precise Not Accurate, Precise

37. Objective C…Error I put the formula for error and % error in your study guide. I put the formula for error and % error in your study guide. The error is the difference between the experimental value and the actual or true value. We take the “absolute value” because there’s no such thing as “negative error.” The error is the difference between the experimental value and the actual or true value. We take the “absolute value” because there’s no such thing as “negative error.” Being 5% high is the same as being 5% low. You still have 5% error in either case. Being 5% high is the same as being 5% low. You still have 5% error in either case.

38. Objective C…Error If the actual value is 10, it doesn’t matter if you get 9 or you get 11. You are still off by a unit of “1” If the actual value is 10, it doesn’t matter if you get 9 or you get 11. You are still off by a unit of “1” % error = Error / True Value x 100 % error = Error / True Value x 100 Using our example, % error = 1/10 x 100 or 10%. Using our example, % error = 1/10 x 100 or 10%.

39. Objective C…Error We will discuss error primarily in our labs. Be sure to include a discussion of any errors that happened in your experiment in your “Analysis of Data” section of your lab report. We will discuss error primarily in our labs. Be sure to include a discussion of any errors that happened in your experiment in your “Analysis of Data” section of your lab report. What kind of errors can you have in your labs? What kind of errors can you have in your labs? Two kinds: Two kinds: Random Random Systemic Systemic

40. Objective C…Error http://www.budapesthotels.com/sitepic/error_button.png http://images.intomobile.com/wp-content/uploads/2009/06/easy-button.jpg Random errors are mistakes. You can take care to reduce or eliminate random errors. These usually come from being unprepared (not reading the lab prior to doing it), rushing to get done, and careless errors (like forgetting to do a step). Random errors are mistakes. You can take care to reduce or eliminate random errors. These usually come from being unprepared (not reading the lab prior to doing it), rushing to get done, and careless errors (like forgetting to do a step). Systemic errors are errors that are present in your system. You can’t do anything about these. If your data is precise, but not accurate this might indicate that you had systemic error. Systemic errors are errors that are present in your system. You can’t do anything about these. If your data is precise, but not accurate this might indicate that you had systemic error. Easy Button Error Button

41. Objective d…Significant Figures http://www.musicdirect.com/shared/images/products/large/aayremyrtle. http://becauseican.co.za/wp-content/uploads/2008/04/ruler_0_10.jpg http://mrsdlovesscience.com/meniscusirr.jpg Measure the block of wood using the ruler. How long is it? Measure the block of wood using the ruler. How long is it? How much water is in the graduated cylinder? How much water is in the graduated cylinder? 23.0 mL?? mL

42. Objective d…Significant Figures When you take measurements in Chemistry class or in lab, you have to worry about how many significant figures (usually abbreviated as sig figs) you have. When you take measurements in Chemistry class or in lab, you have to worry about how many significant figures (usually abbreviated as sig figs) you have. What are sig figs? What are sig figs? All the digits you can read and the first one you can estimate. All the digits you can read and the first one you can estimate. Between 7.1 and 7.2, so record as 7.15. All 3 digits are significant, because you read the first 2 and estimated the last 1.

43. Objective d…Significant Figures http://www.freefoto.com/images/2000/98/2000_98_1---Number-Zero_web.jpg However, if you didn’t measure it, there are rules for figuring out how many sig figs something has. However, if you didn’t measure it, there are rules for figuring out how many sig figs something has. RULE #1. All non-zero digits are significant. RULE #1. All non-zero digits are significant. So that means that the only thing you have to determine is whether or not the zeros are significant. So that means that the only thing you have to determine is whether or not the zeros are significant. Significant? Maybe or maybe not!

44. Objective d…Significant Figures Rules are in the study guide. Rules are in the study guide. 2. Zeros between non zero digits are significant. So, 2.003 has 4 sig figs. 2. Zeros between non zero digits are significant. So, 2.003 has 4 sig figs. 3. Zeros at the end of a number AND to the right of the decimal point are significant. So, 1.000 has 4 sig figs. 3. Zeros at the end of a number AND to the right of the decimal point are significant. So, 1.000 has 4 sig figs. 4. Zeros at the beginning of a number are never significant. So, 0.00034 has 2 sig figs. 4. Zeros at the beginning of a number are never significant. So, 0.00034 has 2 sig figs. 5. Exact measurements or exact quantities have an unlimited amount of sig figs. Example 1 hour = 60 min. “1” and “60” both have an unlimited number of sig figs. 5. Exact measurements or exact quantities have an unlimited amount of sig figs. Example 1 hour = 60 min. “1” and “60” both have an unlimited number of sig figs.

45. Objective d…Significant Figures Adding/Subtracting Adding/Subtracting Answer cannot have more sig figs AFTER the decimal point than the number with the lowest number. Answer cannot have more sig figs AFTER the decimal point than the number with the lowest number. Ex: 2.1 + 2.22 + 2.345 = 6.665 Ex: 2.1 + 2.22 + 2.345 = 6.665 Answer can only have 1 digit after the decimal Answer can only have 1 digit after the decimal Correct answer = 6.7 Correct answer = 6.7 Multiplying/Dividing Multiplying/Dividing Answer cannot have more sig figs than the number with the lowest number of sig figs. Answer cannot have more sig figs than the number with the lowest number of sig figs. Ex: 2.22 x 2.345 = 5.2059 Ex: 2.22 x 2.345 = 5.2059 2.22 has 3 sig figs and 2.345 has 4 sig figs. Answer can only have 3 sig figs. 2.22 has 3 sig figs and 2.345 has 4 sig figs. Answer can only have 3 sig figs. Correct answer = 5.21 Correct answer = 5.21 ±1 sig figs off is usually OK. If answer should have 4 sig figs and you have 3, 4 or 5, I won’t mark it wrong.

46. Objective d…Significant Figures http://www.tvguide.com/celebrities/stuart-scott/214001 But isn’t 50 and 50.0 and 50.00 and even 50.000 the exact same number? Maybe, outside of chemistry class, but not in here. Let me explain. 50 ≠ 50? Wha-hap- happen?

47. Objective d…Significant Figures 50 means that your measurement is somewhere between 49 and 51. 50.0 means that your measurement is somewhere between 49.9 and 50.1 50.00 means that your measurement is somewhere between 49.99 and 50.01 50.000 means that your measurement is somewhere between 49.999 and 50.001 The more sig figs in your measurement, the more confidence you have that it’s “exactly” 50 mL or g.

48. Objective e…SI Units AKA The Metric System http://www.boston.com/ae/celebrity/more_names/blog/KG.JPG You need to know THESE: You need to know THESE: Meters for length (m and cm and nm) Meters for length (m and cm and nm) Kilograms for mass (kg and g) Kilograms for mass (kg and g) Kelvin for temperature (K) Kelvin for temperature (K) cm 3 or liters for volume (L and mL) cm 3 or liters for volume (L and mL) Kilopascals for pressure (KPa and atm) Kilopascals for pressure (KPa and atm) 1.0 KG?

49. Objective e…SI Units AKA The Metric System You need to know You need to know Kilo means 1000 times (1 g = 1 kg) Kilo means 1000 times (1 g = 1 kg) Centi means 1/100 th (100 cm = 1 m) Centi means 1/100 th (100 cm = 1 m) Milli means 1/1000 th (1,000 mm = 1 m) Milli means 1/1000 th (1,000 mm = 1 m) Micro means 1/1,000,000 th (1000 μg = 1 mg or 1,000,000 μg = 1 g) Micro means 1/1,000,000 th (1000 μg = 1 mg or 1,000,000 μg = 1 g) Nano means 1/1,000,000,000 th (1 billion nm = 1 m) Nano means 1/1,000,000,000 th (1 billion nm = 1 m) Å = Angstrom means 1/10,000,000,000 th (10 billion Å = 1 m) Å = Angstrom means 1/10,000,000,000 th (10 billion Å = 1 m) μ (mu) = micro Certified SI Genius

50. Objective f…Density http://www.tungsten-spheres.com/density_model.jpg Density = mass / volume Density = mass / volume Usually has units of g / cm 3 Usually has units of g / cm 3 Density of water = 1.000 g / cm 3 Density of water = 1.000 g / cm 3 You should memorize this number! You should memorize this number! Density is the mass in grams of 1 cubic centimeter of volume. Density is the mass in grams of 1 cubic centimeter of volume. Densely packed

51. Objective f…Density http://www.stevespanglerscience.com/img/cache/bcb9b8db117ee64376aedaf7af3595ca/sevenlayer-2- 51908.jpg Higher density layers on the bottom and lower density layers on the top. Is oil more or less dense than water? D = m / V

52. Objective g…Ice Floats http://www.dharma.org/ims/images/pi_ice_on_pond.jpg Why does ice float? Why does ice float? Why is this a good thing? Why is this a good thing? Ice is actually kind of strange. Actually water is a very unique compound. Ice is actually kind of strange. Actually water is a very unique compound. Most substances are more dense as a solid than they are as a liquid. Most substances are more dense as a solid than they are as a liquid. Ice is an exception. Ice is an exception.

53. Objective h…Take your Temperature! We don’t use Fahrenheit in this course. We don’t use Fahrenheit in this course. We use Celcius (°C) We use Celcius (°C) We also use Kelvin. We also use Kelvin. K = °C + 273 K = °C + 273 0 K is called “absolute zero.” Absolute zero is the temperature at which all molecular motion stops. 0 K is called “absolute zero.” Absolute zero is the temperature at which all molecular motion stops. View outside my little cuz’s high school Chem class in Miami. Probably a balmy 35°C (308K)

54. Objective h…Take your Temperature! http://www.avogadro.co.uk/miscellany/t-and-p/thermometers.gif Kelvin temperature was defined to be a measure of the kinetic energy of the sample of matter. Kelvin temperature was defined to be a measure of the kinetic energy of the sample of matter. A sample of matter at 300K has twice as much kinetic energy as a sample of matter at 150K. Temperature is directly proportional to kinetic energy. A sample of matter at 300K has twice as much kinetic energy as a sample of matter at 150K. Temperature is directly proportional to kinetic energy. You must remember how to convert from °C to K and vice versa. It WILL be on the test. You must remember how to convert from °C to K and vice versa. It WILL be on the test.

55. The Mole http://www.naturephoto-cz.com/photos/others/european-mole-22725.jpg http://www.waukeganschools.org/cspchem/stories/storyReader$12 No, not this guy. No, not this guy. A mole is a “counting unit.” A mole is a “counting unit.” For example, a dozen is 12 of anything. For example, a dozen is 12 of anything. A “mole” is 6.02 x 10 23 of anything. A “mole” is 6.02 x 10 23 of anything. 1 mole of carbon has 6.02 x 10 23 carbon atoms (or particles) and has a mass of 12.0 g (hint, hint: look on the periodic table and find the mass of C in the top left corner). 1 mole of carbon has 6.02 x 10 23 carbon atoms (or particles) and has a mass of 12.0 g (hint, hint: look on the periodic table and find the mass of C in the top left corner).

56. The Mole Section 7.1, pg 170-181 we will do Section 2 and 3 in Chapter 7 later. http://i.ehow.com/images/GlobalPhoto/Articles/2100705/PaperSkyscraperwrittenbyDr.Mom-main_Full.jpg Suppose I ask you to count this stack of paper. I need to know how many sheets there are for a class project. Suppose I ask you to count this stack of paper. I need to know how many sheets there are for a class project. You come back in about a minute and tell me, “hey, Mr. Schwartz, there are 1245 pieces of paper there. You come back in about a minute and tell me, “hey, Mr. Schwartz, there are 1245 pieces of paper there. I don’t believe you could’ve counted them that fast, but you assure me the total is correct ± a couple of pages either way. I don’t believe you could’ve counted them that fast, but you assure me the total is correct ± a couple of pages either way. How did she do it?

57. The Mole When I asked for an explanation, the student said, it’s simple. When I asked for an explanation, the student said, it’s simple. I weighed 1 piece of paper. I recorded that weight and then weighed the entire stack. I weighed 1 piece of paper. I recorded that weight and then weighed the entire stack. I divided the total weight by the weight of 1 sheet and that gave me 1245. I divided the total weight by the weight of 1 sheet and that gave me 1245. That’s essentially what we do to count atoms. That’s essentially what we do to count atoms.

58. The Mole We can’t see atoms. We can’t possibly count them, because they are too small. We can’t see atoms. We can’t possibly count them, because they are too small. But we know how much 6.02 x 10 23 of them should weigh. But we know how much 6.02 x 10 23 of them should weigh. Let’s say we have 2.12 g of carbon. How many carbon atoms is that. We know that 1 mole of carbon has a mass of 12.0 g and 1 mole of C contains 6.02 x 10 23 atoms. Let’s say we have 2.12 g of carbon. How many carbon atoms is that. We know that 1 mole of carbon has a mass of 12.0 g and 1 mole of C contains 6.02 x 10 23 atoms.

59. 2.12 g C = 1.06 x 10 23 atoms 2.12g C 1 mole 6.02 x 10 23 atoms 2.12g C 1 mole 6.02 x 10 23 atoms 12 g C 1 mole 12 g C 1 mole Real simple: multiply everything on top. Divid everything on bottom. Cancel out units where you can.

60. 2.12 g C = 1.06 x 10 23 atoms 2.12g C 1 mole 6.02 x 10 23 atoms 2.12g C 1 mole 6.02 x 10 23 atoms 12 g C 1 mole 12 g C 1 mole Notice that g of C cancels out and mole cancels out, leaving us with the units of ATOMS for our answer.

61. 2.12 g C = 1.06 x 10 23 atoms 2.12g C 1 mole 6.02 x 10 23 atoms 2.12g C 1 mole 6.02 x 10 23 atoms 12 g C 1 mole 12 g C 1 mole We really can’t “count” 1.06 x 10 23 atoms. They are too small. But by doing it this way, we can calculate how many we have.

62. Mass of an Element “gram atomic mass” or just atomic mass To find the mass of an element, you look it up on the Periodic Table. To find the mass of an element, you look it up on the Periodic Table. For simpicity, let’s round all the elments to 1 decimal point. For simpicity, let’s round all the elments to 1 decimal point. What is the mass of sodium? Iron? Krypton? Tungsten? Uranium? What is the mass of sodium? Iron? Krypton? Tungsten? Uranium?

63. Mass of a Compound “gram formula mass” (for ionic compounds) or “gram molecular mass” (for molecular compounds) or just a generic “Molar Mass.” There are no compounds on the Periodic Table. There are no compounds on the Periodic Table. So you take the mass of each element, multiply that times the subscript for that element and then add everything together to get the mass of the compound. So you take the mass of each element, multiply that times the subscript for that element and then add everything together to get the mass of the compound. Ex: mass of CO 2 = 12 + 16 x 2 = 12 + 32 = 44 Ex: mass of CO 2 = 12 + 16 x 2 = 12 + 32 = 44 What is the mass of water (H 2 O)? Rust (Fe 2 O 3 )? Table Sugar (sucrose = C 12 H 22 O 11 )? Salt (NaCl)? What is the mass of water (H 2 O)? Rust (Fe 2 O 3 )? Table Sugar (sucrose = C 12 H 22 O 11 )? Salt (NaCl)?

64. Power Point Assignment If your last name ends in A-L If your last name ends in A-L Pg 181, 12-14 (a and b only) Pg 181, 12-14 (a and b only) Pg 198, 46 (b and d), 48, 50 (b, d and f) Pg 198, 46 (b and d), 48, 50 (b, d and f) If your last name ends in M-Z If your last name ends in M-Z Pg 181, 12-14 (b and c for 12; c and d for 13 and 14) Pg 181, 12-14 (b and c for 12; c and d for 13 and 14) Pg 198, 46 (a and c), 48, 50 (a, c and e) Pg 198, 46 (a and c), 48, 50 (a, c and e) Both groups be prepared for a one-question quiz on Chapter 7 material in this powerpoint. Both groups be prepared for a one-question quiz on Chapter 7 material in this powerpoint.

65. The End What is next? Well, Chapter 5, 28, 13, and 14. If you are in advanced Chemistry, we are going to do all of those in Unit 2 (5&28) and 3 (13&14) If you are in Chemistry, it’s mostly going to be Chapter 5, with a little bit of all the others thrown in. We are going to skip quite a lot in 28, 13 and 14, however.