About you! Largest groups by college: Largest groups by major: Hobbies 1 Favorite music groups: Lemme Know! 2 Why you’re here (Fall 2011) To get a degree, add a degree to all my experience My parents will disown me if I don’t earn a degree To better myself, to become a lawyer To get smart, to prove my parents wrong Math degree, so I can teach To get an education in something I enjoy.. To prove my parents wrong/ Better than being homeless To party! Make my parents proud To get a good job Last resort, didn’t have a choice Something beautiful about studying ideas. Get wealthier I value education Secure future To make a difference in peoples’ lives To learn entrepreneurship 3 Syllabus summary: Book Russo (not me!) & Silver book: advised…or make a friend Mastering Chemistry: required Alternate book: advisable Virtual book: how I see things = lecture CEF study guides: Factoids that are useful; anything in them is fair game for exams! Problems from book: required Fun books: Cartoon Guide to Chemistry & P.W. Atkins’ Molecules 4 Syllabus Summary: Homework & Grades 3 varieties of homework Assigned-but-not-graded (tied to unannounced quizzes in lecture) Recitation Topics (tied to unannounced quizzes) Mastering Chemistry on-line assignments ING13: an “A” grade means you can go BEYOND what was taught. Approximate Grade Breakdown (see actual syllabus) Quizzes: 45% Graded Homework (mostly MC on-line): 20% Midterms: 20% (3 midterms, drop lowest) Final: 30% of possible points Early Performance Bonus: 2.5% Exit Tickets: 3.5% (depends on group performance!) That’s 120%! Anything over 90% = A. Anything over 80% = B, etc. 5 There is much other stuff in the syllabus, so please read it all. Thank you. 6 Announcements This Friday, we will meet here in Lockett again….I am told we will have the TAs assigned soon so you can do stuff on Fridays. Yay. We will try to get 450 quiz points by end of the course. We better start soon. ING13: there is no study guide but ABNG problems. The first MC assignment has been posted. Due Friday, Feb. 1, 11:59 pm. Do it sooner! We are about one day behind…don’t worry about it. 7 Whaddya know…it’s time to talk about chemistry in some detail! It is the subject of matter on a very fine scale. What’s Matter? 8 Matter has mass and occupies space. A solution is a very fine mixture that eventually happens without mechanical agitation. 9 A doughnut is the same as a coffee cup (or a beer mug). Can anyone think of a way to make a material do this? A doughnut is the same as a coffee cup (or a beer mug). http://en.wikipedia.org/wiki/Topology 10 Hey….if we could change coffee cups into donuts, we could do something dangerous and fun, like make Wolverine claws! Wolverine claws as we dangerously dream of them: http://www.youtube.com/watch?v =LPmbGzQaOCs&playnext=1&list= PLD8C557850FB35C59 http://www.youtube.com/watch?v=LPmbGzQaOCs &playnext=1&list=PLD8C557850FB35C59 Wolverine claws as we actually can make them: http://www.youtube.com/watch?v=j0cs9j7HT-g http://www.youtube.com/watch?v=j0cs9j7HT-g 11 We need details about that matter definition: has mass and occupies space. •Mass: how easy is it to accelerate the object. F = ma •Acceleration: change in speed with time (dv/dt = d2x/dt 2 for you Calculus experts) •Gravity provides a convenient, relatively constant, acceleration: F = mg where g = 9.8 ms-2 12 Mass is measured indirectly • We could define one gram as the mass of one cubic centimeter (or one cc) of water. • Then see how much a spring is compressed with this mass on it under Earth’s gravity. • For a good spring, an object that compresses it 2x more than one cubic cc of water must have 2 grams of mass. • When you weigh something, you indirectly obtain its mass. • The thing really being measured is a force, which has other units (kgms-2). • We’ll practice with compound units soon. 1 cm 1 cm 1 cm 13 Here’s a picture of a spring scale. If you look at old scales of good quality, they will often proudly proclaim “No Springs”. Why? http://www.medicalscale1.com/wp-content/uploads/2011/01/spring-scale.jpg It actually took awhile to find a spring scale on the web---most scales today are digital. Probably a piezoelectric transducer, not springs. I have yet to see one that says “no transducers”. 14 How would you measure mass without gravity? View from inside the space station. 15 http://spaceflight.nasa.gov/gallery/images/station/ Matter Occupies Space What’s Space? What does it mean to “occupy” space? In fact, for almost anything you can name, most of the space is not occupied! Before we can understand that, we have to have ways to measure physical properties. 16 Space means volume. Our favorite unit of length in chemistry is often the centimeter: one-hundredth of a meter. Volume is length x width x height, or cm3 1 cm 1 cm 1 cm 1 cm3 of water is one milliliter of water (one one-thousandth of a liter, and a liter is almost the same volume as a quart.) Maybe we should write this as 13 cm3 17 Let’s practice some volume and area calculations. 18 The next part of the lecture is brought to you by the number… 2 Chapter 2 is about Quantitation, units and energy. 19 How many creatures can count? “Recent studies…..have uncovered new instances of a counting skill in different species, suggesting that mathematical abilities could be more fundamental in biology than previously thought. Under certain conditions, monkeys could sometimes outperform college students.” --Scientific American, September 15, 2009 One monkey was able to choose between two sets of identical objects, differing only by the number of objects in the set. It was slightly less accurate than college students at doing this, but it was faster. This suggests the monkey was less afraid of making mistakes. Because there was a reward for performance (Kool Aid) the non-chagrinned monkey moved on quickly to the next round. Freshmen apparently were more tentative about making mistakes. Probably a lesson here for college students and entrepreneurs. BTW, the blog after the article is intriguing, too—a little bit funny and a little bit sad. http://www.scientificamerican.com/article.cfm?id=ho w-animals-have-the-ability-to-count http://www.scientificamerican.com/article.cfm?id=how-animals-have-the-ability-to-count Clever Hans, a German horse that could count, ca. 1910. There is a Clever Hans effect in Psychology, traced to this animal. Some animals (people, too?) Detect subtle body language cues and respond according to those. That is how Clever Hans could count. It was not a fraud—the animal just sensed tension in the People answering the question…only if those people actually knew the answer to it. Wikipedia article on Clever Hans 20 Words matter! Precision is not Accuracy. It is possible to be consistently wrong. The difference between the right word and the almost right word is really a large matter — it's the difference between a lightning bug and the lightning. Mark Twain (Samuel Clemens) http://www.metacafe.com/watch/44666/like_no_other/ 21 What does this read? 60 40 20 80 The last number you report is always a guess! 100 120 140 The uncertainty is something like 1/10th of a decimal scale; here that is 2 mph. Noise: if the speedometer wiggles, it adds even more uncertainty. 22 Some scales go by halves (thankfully) How long is the pink line? What’s the uncertainty here? Drag divisors to split the scale by twos 24 This joke is from Prof. Pojman: the guy with the tie. A class is touring the Museum of Natural History on a field trip, and a kid asks the guide, “How old is this dinosaur?” The guide replies, “Sixty million years and six months.” The teacher is astonished: “How can you tell the age so precisely?” “I dunno,” says the guide. “When I started working here six months ago, they told me 60 million years.” 25 Significant Figures…just keep it reasonable (please!) Wrong Right Why 1.867 + 2 = 3.867 1.867 + 2 = 4 Addition/Subtraction: use least precise places 1.867 + 2.000 = 4 1.867 + 2.000 = 3.867 1.867 x 2 = 3.734 1.867 x 2 = 4 1.867 / 2.000 = 1 1.867/2.000 = 0.9355 " Multiply/Divide: use smallest number of significant figures " In this class, if it’s really a problem about significant figures, you must get it exactly right. If the problem is about something else, just try not to look ridiculous. 26 Decimal points make things real. 2000 means 1900 to 2100 2000. means 1999 to 2001 2000.0 means 1999.9 to 2000.1 27 A problem can come when you use numbers ending in zero in a sentence. The meter reading was 2000. What does THAT mean? Is the period there to end the sentence or describe the number’s precision? The meter reading was 2.000 x 103. Unambiguous! It means between 1999 and 2001 or….. 1.999 x 103 to 2.001 x 103 28 Announcements We will NOT meet here on Friday. We don’t know exactly where we will meet yet, but…. watch for email. Surely, it will be near Choppin and Williams Halls. Download & attempt Recitation Topics 1 from website. 29 Exponential (Scientific) Notation Avogadro’s number (the number of H2O molecules in 18.0 grams of water): 602,000,000,000,000,000,000,000 = 6.02 x 1023 Age of universe in seconds (somebody’s guess): 300,000,000,000,000,000 s = 3 x 1017 Learn to type exponents efficiently into your calculator! (The E or EEX button) 30 Exponent rules 2x2x2= (23 )3 = 23 29 = 23 x 24 = 27 =8 83 = 512 m m x x m = m3 (m3 )4 = m12 m3 x m4 = m 7 These rules make sense when you write them out term by term. e.g. (23 )3 = 29 = 83 = 512 (2· 2· 2)3 = (2· 2· 2) · (2· 2· 2) · (2· 2· 2) = 29 31 You can nudge the tens powers, but usually we don’t leave it that way. 3.1 x 1017 is the same as 31 x 1016 Handy if you must add 2 x 1016 to 3.1 x 1017 3.1 x 1017 + 2 x 1016 <<<Nudge<<< 31 x 1016 + 2 x 1016 Result: 33 x 1016 >>>De-Nudge>>> 3.3 x 1017 32 Suppose a speeding ticket is $50 plus $10 x MPH in excess of speed limit (60 MPH). What is the range of costs for that speeding ticket if your car can go 125 MPH? 35 S.I. units were not chosen entirely by chemists. Length Mass Time Temperature Number of something Electric current Luminous intensity Meter Kilogram Second Kelvins Mole Ampere Candela The original idea of the meter was that there would be 1 x 107 of them between the equator and the North Pole. The units have an unusual history! On some other planet—did you know there are billions of planets?—perhaps some other form of intelligent life is using altogether different units. Here in the USA, we still dislike the SI units. Even most chemists prefer gram to kilogram, centimeter to meter, etc. 36 Larger than Smaller than Prefixes—yes, you have to memorize them. Prefix Example Example means Nano Nanometer 0.0000000001 m or 10-9 m Micro Microliter 0.000001 L or 10-6 L Milli Milligram 0.001 gram Centi Centimeter 0.01 meter Deci Deciliter 0.1 liters (= 100 milliliters, by the way) Deka Dekameter 10 meters Hecto Hectogram 100 grams Kilo Kilometer 1000 meters (=0.6 miles, by the way) Mega MegaHz 1000 cycles per second, once a very fast computer! Giga GigaHz 1,000,000 = 106 cycles per second, now an OK computer (barely) 37 You can do anything you want to both sides of an equation. 1 mile 5280 feet Divide both sides by 5280 feet 1 mile 1 5280 feet Divide both sides by 1 mile 5280 feet 1 1 mile 38 And you can multiple anything by 1 without changing it…except you might change the units. A marathon is 26.4 miles. What’s that in feet? 26.4 miles X 5280 feet 139392feet 1 mile Is the number of significant figures correct? 39 Announcements MT1 should be available tonight. Unless you are pre-educated, you should WAIT! Sign up for EITHER no-calculator OR with-calculator. Yellow notes template forms available. You MUST relinquish these when you leave the testing center. Schedule on website has been pushed back a day or so. 40 Sample problems How many clock cycles does a 3GHz Pentium computer go through in one day? How many molecules of water in a nanogram of water? 41 The cost of disputing a grade. In 1975, a promising young chemistry major drove 42 miles from his new university to his old one to dispute a grade with the math department. If the 1967 Ford Galaxie got 17 miles per gallon, and if gasoline cost $0.54/gallon, what was the cost? 42 Let’s do a basketball question. A basketball court measures 94’ x 50’. Compute its area in square yards. If you were the professor, how would you modify this question for a quiz? 43 I married my lawnmower. My yard consists of 3 major segments measuring (in feet) 70 x 30, 100 x 10 and 30 x 40. Can my wife use one of the new battery-powered lawnmowers without recharging? The lawnmower I am considering claims it can do 1/3 acre without recharging. Convert is free on TigerWare or use your smartphone. 44 Let’s give it a try. Easy way that works here. Prim and proper way that always works. 45 Practice! http://www.youtube.com/watch?v=vjvJHsJD8ic http://www.youtube.com/watch?v=vjvJHsJD8ic This scene is about 1:20 into the video 46 Many important properties have compound units. Density is the mass per unit volume. For example, the liquid mercury in a thermometer has a density of 13.6 grams per cubic centimeter. Units of density: Billiard ball floating in mercury. http://www.zyra.org.uk/mercury3.htm g g 3 cm mL 47 Why do we care? 1. Density is an important, easily measured property that lets us gauge the purity of substances. 2. Heavy stuff sinks, so that tells us what we might have to do to, say, clean up a hazardous waste site. http://www.whistleblower.org/article.php?did=18&scid=28 http://murray.senate.gov/hanfordcleanup/index.cfm The Hanford Nuclear Site: 50 million gallons (more?) of contaminated wastes on the beautiful Columbia River. Pricetag to clean: $40,000,000,000 = $4 x 1010. (I have seen much higher estimates, too). 48 Or we could care just because density lets us do fun stuff. http://www.youtube.com/watch?v=u19QfJWI1oQ http://www.youtube.com/watch?v=u19QfJWI1oQ 49 Another property with a compound unit: force. Defining physical relation F=ma Mass in kilograms, kg Acceleration, m/s2 Resulting physical unit m kg 2 s Called a Newton, nt 50 Still more complex: pressure Defining physical relation P = F/A Force, Newtons Area, m2 Resulting physical unit m 2 nt kg s m2 m2 m s2 kg Called a Pascal, Pa 51 These aren’t the usual units of pressure here in the USA! 101,325 Pa = atmospheric pressure = 14.7 p.s.i. p.s.i. = pounds per square inch Example: most cars use 32 p.s.i. in their tires. What’s that in Europe? Harder (but fun) problems coming in the Recitations. 52 Conversions Figure out the smaller unit. You will need a larger number of those. Example: Q. How many deciliters in 10 Liters? A. Deciliters is smaller, so you will need more of them. Ten deciliters for each liter times 10 liters = 100 deciliters. 53 Or, you can do it very prim and proper 1. Write the given: 10 liters 2. Write the conversion: 1 deciliter = 0.1 liter 1 deciliter 1 3. Divide both sides of the conversion by right side: 0. 1 Liter 4. Divide both sides of the conversion by left side: 1 0.1 Liter 1 deciliter 5. Multiply the “given” from step 1 with whichever form of the number “1” from steps 3-4 cancels the undesired unit. 1 deciliter 10 Liter 100 deciliters 0.1 Liter 54 Learn to line conversions out. 1 deciliter 10 Liter 100 deciliters 0.1 Liter Start by putting what you want at the left. Arrange conversion factors so as to cancel out the unit you do not want! 55 Despite the metric system, you must still to be able to convert between different unit systems. Example: the smallest MOPAR V8 engine of 1965 was 273 cubic inches. Today, we’d quote that in liters, but how many liters? Reason it out: A liter is like one quart, a cubic inch is like your thumb. Going from cubic inches to liters should result in a smaller number. 1 inch = 2.54 centimeters (memorize!) 3 1L 2.54 cm 1 mL 273 in 4.5 L 3 1 in 1 cm 1000 mL 3 3 3 2.54 cm 273 in 3 1 in 1 mL 1 L 1 cm 3 1000 mL 4.5 L 56 You may find it much easier at first to do these problems one step at a time. For example, just compute the conversion factor for in3 to cm3 first. 1 inch 2.54 cm Cube both sides 1 inch (2.54) cm 16.4 cm 3 3 3 3 3 Now what? 57 What pressure do I exert on my feet? English System Metric System P = Force/Area = weight in pounds /area in square inches P = Force/Area = mass x gravity /area in square meters 58 BTW, if pounds in the English system really is a unit of force, what is the English unit of mass? http://hypertextbook.com/physics/foundations/system-english/ http://en.wikipedia.org/wiki/Slug_(mass) 59 Problem: estimate the volume of this room in milliliters. This will also teach us a bit about scientific notation. 60 Mapping: conversions that involve more than multiplication & division. Example: Centigrade to Fahrenheit o o F 32 C 1.8 o 212 Slope = 1.8 oF 32 o F 1.8 C 32 0 100 oC 61 The centigrade scale is coarser… centigrade divisions are bigger. An 18-degree change in Fahrenheit temperature is a 10-degree change in Centigrade. o F 32 C 1.8 o o o F 1.8 C 32 62 Kelvin temperature is just offset from centigrade. The “step size” (degree size) is the same, though, because the slope = 1. BTW, why 273.15 ??? K = oC + 273.15 K Slope = 1 273.15K = 0°C 0 Zero K = -273.15°C 0 oC 63 Converting oC to oF in your head Double the oC temperature. Subtract 10%. Add 32. 64 Converting oF to oC in your head Subtract 32 Divide by 2 Add 10%. It’s worth remembering some temperatures. 16 oC = 61 oF July in Duluth = February in Baton Rouge 10 oC = 50 oF May in Minnesota =January in Baton Rouge 98.6 oF = 37 oC Body Temperature = Summer in Dallas - 40 oF = - 40 oC Winter in Minnesota, but hardly the coldest day there (record = -60oF) 100 oF 77 oF = 25 oC 77 K = -196.15 oC = -321 oF Rectal temperature of the cow Room Temperature Liquid N2 66 Now, let’s turn to a study of temperature, energy and power – what ARE these? But first, remember that Sony movie with the bouncing balls. http://www.metacafe.com/watch/44666/like_no_other/ 67 Whiteboard or ELMO presentation of energy, to include: W = DE = mad Q = m C DT calorie, Calorie and Joule How crazy it is that this all goes back to choosing meter as our length and gram as the mass of 1 cm3 68 The heat capacity equation involves CHANGES in temperature. Q C m DT Q = heat added ∆T = temperature CHANGE WHY does Gold have such a low heat capacity? High heat capacity: the material remains “cool” about having heat added to it. Example: water. Low heat capacity: the material gets hot quickly if heat is added to it. Example: gold. Heat Capacity…or why it is actually not hot in Baton Rouge in the summer We mentioned that water had high heat capacity. Water also forms the basis for defining heat capacity. Heat capacity is how much energy it takes to raise the temperature of something by a certain amount. Define: 1 calorie = the amount of energy required to raise 1.00 grams of water by 1.00 degree centigrade. Note: a "food calorie" is actually 1000 calories! SI unit of energy is the Joule: 1 calorie = 4.184 Joules A CHANGE in temperature is the same in Kelvins as in degrees centigrade! T1 = 0oC = 273K T2 = 10oC = 283K ∆T = 10oC = 10K Define: A calorie is the heat required to raise 1 mL (1 g) of water by 1 degree Centigrade (e.g., by 1 Kelvin) 71 Stop here? 72 Assume you are mostly water, then estimate how many calories it takes to raise your body temperature from its normal 98.6oF to a fever condition of 101oF. Convert this to Joules.