CHM 1045 Fall Unit I. Lecture slides from August 27 to September 21. Exam One is Wednesday, Sept 26. air 80% nitrogen 20% oxygen.

Transcription

1 CHM 1045 Fall 2018 Unit I Lecture slides from August 27 to September 21. Exam One is Wednesday, Sept 26. air 80% nitrogen 20% oxygen helium 1

2 air 80% nitrogen 20% oxygen helium 2

3 The process of deep-frying can be divided into four stages: (1) Initial heating. The surface of the food reaches the boiling point of water. (2) Surface boiling. The hot oil surrounding the food causes water inside the food to evaporate. (3) Decreasing heat transfer rate. Crust continues to dehydrate, less heat conduction, rate of heat transfer through escaping steam decreases (reduced bubbling). The remaining moisture inside of the food is slowly heated to the boiling point of water, which cooks the food inside as if it were boiled, gelatinizing the starch and denaturing the proteins in the food. (4) Bubble end point. Water from inside the food is no longer evaporating. Remove the fried food before it begins to absorb oil. 3

4 Indiana Jones and the Raiders of the Lost Arc Paramount, 1981 Assuming the statue is solid gold, how much will it weigh? A. 10 lb B. 20 lb C. 40 lb D. 80 lb E. 160 lb 4

5 5

6 ¼ gallon = 1 quart = liters 1 gallon ½ gallon 1 quart 1 liter /01/20/fresh-raw-milk-on-tap-in-turin/ Assuming the statue is solid gold, how much will it weigh? A. 10 lb B. 20 lb C. 40 lb D. 80 lb E. 160 lb 6

7 Assuming the statue is solid gold, how much will it weigh? A. 10 lb B. 20 lb C. 40 lb D. 80 lb E. 160 lb A Partial History of the Number Zero 7

8 8

9 René Descartes ( ) Daniel Gabriel Fahrenheit German physicist 1709, alcohol thermometer 1714, mercury thermometer 1724, Fahrenheit Scale, allowed temperatures to be recorded reproducibly. 9

10 Anders Celsius Swedish astronomer 1742, devised the centigrade or "Celsius scale" 0 K 10

11 900 megahertz, 21.1-tesla NMR magnet at the FSU National High Magnetic Field Laboratory (Mag Lab) liquid helium 4.2 K As temperature increases, in general, the density of a substance will A. increase B. decrease C. remain the same 11

12 How much does it cost to drive from Tallahassee to Miami? 12

13 Increasing from 8 pounds to 16 pounds, at what weight does a bowling ball sink? A. 11 lb, or less B. 12 lb C. 13 lb D. 14 lb E. 15 lb, or more 13

14 14

15 Triboelectric Series Become positive in charge The following materials will tend to give up electrons when brought in contact with other materials. They are listed from those with the greatest tendency to give electrons to those that barely give up electrons. Dry human skin Greatest tendency to giving up electrons and becoming highly positive (+) in charge Leather Become negative in charge The following materials will tend to attract electrons when brought in contact with other materials. They are listed from those with the least tendency to attract electrons to those that readily attract electrons. Rabbit fur Fur is often used to create static electricity Wood Attracts some electrons, but is almost neutral Glass The glass on your TV screen gets charged and collects dust Human hair "Flyaway hair" is a good example of having a moderate positive (+) charge Nylon Wool Lead A surprise that lead would collect as much static electricity as cat fur Cat fur Silk Aluminum Gives up some electrons Paper Neutral There are very few materials that do not tend to readily attract or give up electrons when brought in contact or rubbed with other materials. Amber Hard rubber Nickel, Copper Brass, Silver Gold, Platinum Polyester Styrene (Styrofoam) Saran Wrap Polyurethane Polyethylene (like Scotch Tape) Polypropylene Some combs are made of hard rubber Copper brushes used in Wimshurst electrostatic generator It is surprising that these metals attract electrons almost as much as polyester Clothes have static cling Packing material seems to stick to everything You can see how Saran Wrap will stick to things Pull Scotch Tape off surface and it will become charged Cotton Best for non-static clothes Vinyl (PVC) Many electrons will collect on PVC surface Steel Not useful for static electricity Silicon Teflon Greatest tendency of gathering electrons on its surface and becoming highly negative (-) in charge 15

16 Assuming the lowest charge corresponds to having only one electron transferred to the oil drop, implies... (4.8 x C)/(1.6 x C) = 3 3 e (3.2 x C)/(1.6 x C) = 2 2 e (6.4 x C)/(1.6 x C) = 4 4 e (1.6 x C)/(1.6 x C) = 1 1 e (4.8 x C)/(1.6 x C) = 3 3 e An effort to reconstruct Millikan's "exemplary" experimental thinking revealed serious discrepancies between Millikan's notebooks and his published "raw" data (Holton, 1978). The numerous notes which are scattered across the pages cast further doubt on Millikan's integrity: This is almost exactly right & the best one I ever had!!! [20 December 1911] Exactly right [3 February 1912] Publish this Beautiful one [24 February 1912] Publish this surely / Beautiful!! [15 March 1912, #1] Error high will not use [15 March 1912, #2] Perfect Publish [11 April 1912] Won't work [16 April 1912, #2] Too high by 1½% [16 April 1912, #3] 16

17 The notebooks reveal that, indeed, substantial data are missing from Millikan's published reports. Of 175 total drops documented in the notebooks, only 58 (barely one-third) appear in the final paper. By contrast, Millikan had announced in his 1913 paper that "It is to be remarked, too, that this is not a selected group of drops but represents all of the drops experimented on during 60 consecutive days, during which time the apparatus was taken down several times and set up anew" [his own emphasis!]. In his 1917 book, The Electron, he repeats this statement and then adds, "These drops represent all of those studied for 60 consecutive days, no single drop being omitted. At first blush, this outrageous violation of scientific integrity would seem to discredit Millikan's findings. Even if one assumes that standards of reporting data earlier in the century were less rigorous, Millikan clearly misrepresented the extent of his data. One may caution students, however, that we may not want to conclude that therefore there was no good, "scientific" basis for his selective use of data. A more complete analysis of Millikan's notebooks, in fact, and of the nature of the experimental task that they crudely document, reveals more tellingly the reasons that Millikan included some drops and excluded others. 17

18 18

19 19

20 Iodine-131 is used to image the brain and monitor thyroid activity, but it is also a byproduct of nuclear fusion and causes cancer. An 131 I nucleus contains: A. 53 protons and 78 neutrons B. 53 protons and 131 neutrons C. 78 protons and 53 neutrons D. 131 protons and 53 neutrons E. 131 protons and 78 neutrons 20

21 A. S B. Se C. Se 2 D. Br E. Br 2 21

22 22

23 one dozen donuts = 12 donuts one ream paper = 500 sheets of paper one gross lightbulbs = 144 lightbulbs one mole water molecules = 602,200,000, ,000,000,000 water molecules You are throwing a party for 12 people. Assume each person will eat 9 shrimp. How many pounds of 18-count shrimp should you buy? A. 3 lbs B. 6 lbs C. 9 lbs D. 12 lbs E. 15 lbs 23