Unit 1 Introduction to Chemistry

1. Unit 1Introduction to Chemistry Internet web site: http://old.unit5.org/roller/

2. Material Safety Data Sheet (MSDS) gives information about a chemical -- -- lists “Dos” and “Don’ts;” emergency procedures

3. acuteexposure vs.chronic exposure damage occurs after repeated exposure Chemical Exposure e.g. reaction to drugs or medication e.g. smoking, asbestos a one-time exposure that causes damage

4. How Toxic is “Toxic?” Chemicals may cause harm in many different ways: • Flammable • Explosive • Radioactive • Corrosive • Irritant • Carcinogenic • Mutagenic • Teratogenic

5. LD50 There are various ways an LD50 can be expressed. For example, acetone has the following LD50s: the lethal dosage for 50% of the animals on which the chemical is tested ORL-RAT LD50: 5,800 mg/kg IHL-RAT LD50: 50,100 mg/m3h SKN-RBT LD50: 20 g/kg

6. LD50 Example Chemical A: LD50 = 3.2 mg/kg Chemical B: LD50 = 48 mg/kg Which is more toxic? Chemical A is more toxic because LESS is necessary to kill half of a given population

7. Science

8. the search for knowledge; facts using knowledge in a practical way The Functions of Science e.g., properties of aluminum pure science applied science strong lightweight good conductor

9. Design a face shield to protect and provide clear vision. Corning Glass NASA’s Problem Design a material that is clearand can with- stand extreme differences in temperature without fail- ing (cracking). Corning Glass Company FAILED…but SUCCEEDED at making great cookware that can withstand extremes in temperature.

10. Aluminum Mining • 1850s: aluminum sold for $500 / pound • Charles Martin Hall • Developed method to extract aluminum from bauxite • Hall’s method • 1 pound Al costs $ 0.30 4-6 pounds bauxite + current = 1 lb Al

11. Science attempts to establish cause/effect relationships Science can NEVER prove a cause/effect relationship, only make a correlation…

12. risk-benefit analysis weigh pros and cons before deciding Because there are many considerations for each case, “black/white thinking” rarely applies. It is usually shades of grey.

13. How doesscientificknowledgeadvance? 1. curiosity 2. determination 3. persistence 4. good observations

14. The Scientific Method

15. ** Key: Be a good observer. observationinference uses the five senses involves a judgment or an assumption

16. Types of Data Observations are also called data. qualitative data quantitative data -- -- descriptions measurements e.g., e.g., colorless liquid 17 mL; 83oC (vs. clear liquid)

17. Candle Observation Activity

18. A Description of a Burning Candle A photograph of a burning candle is shown1 in the upper right corner. The candle is cylindrical2 and has a diameter3 of about 3 cm. The length of the candle was initially about 16 centimeters4, and it changed slowly5 during observation, decreasing about 1 cm in one hour6. The candle is made of a translucent7, white8 solid9 which has a slight odor10 and no taste11. It is soft enough to be scratched with the fingernail12. There is a wick13 which extends from top to bottom14 of the candle along its central axis15 and protrudes about 5 mm above the top of the candle16. The wick is made of three strands of string braided together17. A candle is lit by holding a source of flame close to the wick for a few seconds. Thereafter the source of flame can be removed and the flame sustains itself at the wick18. The burning candle makes no sound19. While burning, thebody of the candle remains cool to the touch20 except near the top. Within about 1.5 cm of the top the candle is warm21 (but not hot) and sufficiently soft to mold easily22. The flame flickers in response to air currents23 and tends to become quite smoky while flickering24. In the absence of air currents, the flame is of the form shown in the photograph, though it retains some movement at all times25. The flame begins about 2 mm above the top of the candle26, and at its base the flame has a blue tint27. Immediately around the wick in a region about 2 mm wide and extending about 5 mm above the top of the wick28 the flame is dark29. This dark region is roughly conical in shape30. Around this zone and extending about 1 cm above the dark zone is a region which emits yellow light31, bright but not blinding32. The flame has rather sharply defined sides33 but a ragged top34. The wick is white where it emerges from the candle35, but from the base of the flame to the end of the wick36 it is black, appearing burnt, except for the last 0,5 cm, where it glows red37. The wick curls over about 3 mm from its end38. As the candle becomes shorter, the wick shortens too, so as to extend roughly a constant length above the top of the candle39. Heat is emitted by the flame40, enough so that it becomes uncomfortable in 10 to 20 seconds if one holds his finger 10 cm to the side of the quiet flame41 or 10 – 12 cm above the flame42.

19. a testable prediction Make ahypothesis: Parts of the Scientific Method Repeatedlyexperimentto test hypothesis. procedure: order of events in experiment Identify an unknown. (i.e., a recipe) variable: any factor that could influence the result

20. A ScientificExperiment Experiments must be controlled: Only one variable can change at a time! (Ideally…) conclusion: must be based on the data

21. A Controlled Experiment?

22. Make observation Scientific Method Ask question Develop hypothesis Test hypothesis with an experiment Test hypothesis with further experiments Revise hypothesis Analyze data and draw conclusions Hypothesis IS supported Hypothesis is NOT supported Develop theory Wysession, Frank, Yancopoulos, Physical Science Concepts in Action, 2004, page 8

23. law: states what happens, i.e., a relationship between various quantities -- Laws are often written in the form of… an equation. Scientific Law vs. Scientific Theory -- e.g., Newton’s law of gravity, laws of conservation

24. theory: tries to explain WHY or HOWsomething happens -- based on current evidence Theory of Gravity, Atomic Theory -- e.g., images of nickel atoms taken by an STM a scanning tunneling microscope (STM)

25. Phlogiston Theory of Burning 1. Flammable materials contain phlogiston 2. During burning, phlogiston is released into the air 3. Burning stops when… …object is out of phlogiston, or …the surrounding air contains too much phlogiston. (superceded by combustion theory of burning)

26. Chemistry

27. ~ D ~ D ___ ___ Early practical chemistry: household goods, weapons, soap, wine, basic medicine The Beginning The Greeks believed there were four elements D earthwind firewater

28. . . . . . . . . . . . . . . . (~500 – 1300 C.E.) the quest for the Philosopher’s Stone Alchemy (the elixir, the Sorcerer’s Stone) Allegedly, this substance would turn cheap metals into gold Alchemical symbols for substances… GOLD SILVER COPPER IRON SAND

29. Philosopher’s Stone  COPPER GOLD changing one substance into another transmutation: we cannot transmute elements into different elements In ordinary chemical reactions…

30. Alchemy was practiced in many regions of the world, including China and the Middle East. Alchemy arrived in western Europe around the year 500 C.E. Modern chemistry evolved from alchemy.

31. Contributions of alchemists: • experimental techniques • new glassware • information about elements • developed several alloys

32. What is chemistry? the study of matter and its changes

33. Areas of Chemistry biochemistry organic the study of carbon containing compounds the chemistry of living things inorganic physical studies everything except carbon e.g., compounds containing metals measuring physical properties of substances e.g., the melting point of gold

34. Careers in Chemistry • research(new products) • production(quality control) • development(manufacturing) • chemical sales • software engineering • teaching

35. The skills you will develop by an earnest study of chemistry will help you in any career field.

36. The Scope of Chemistry bulk chemical manufacturing pharmaceuticals acids, bases, fertilizers **sulfuric acid (H2SO4) = #1 chemical petroleum products fuels, oils, greases, asphalt 1 in 10,000 new drugs gets FDA approval synthetic fibers , spandex nylon, polyester, rayon

37. Chemistry impacts: everyone all fields of endeavor

38. Government Regulation of Chemicals The various levels of government regulate chemicals to protect the: worker environment OSHA EPA consumer FDA USDA FAA CPSC

39. Manipulating Numerical Data

40. Graphs

41. # of students Bar Graph shows how many of something are in each category

42. Percentage of Weekly Income Pie Graph shows how a whole is broken into parts

43. Stock Price over Time Line Graph shows continuous change In chemistry… you will always use a line graph.

44. Elements of a “good” line graph 2. axes labeled, with units 1. title 3. neat 4. use the available space

45. Graphing HW Distance Cycled (km) Time (h) Extrapolation: predicting a pattern outside of a data set using the graph Interpolation: estimating a data point within the set of data using the pattern of the graph

46. Essential Mathof Chemistry

47. Form: (# from 1 to 9.999) x 10exponent 800 = 8 x 10 x 10 = 8 x 102 2531 = 2.531 x 10 x 10 x 10 = 2.531 x 103 0.0014 = 1.4 101010 = 1.4 x 10–3 Scientific Notation …used to express very large or very small numbers. Also used to maintain correct SF. (+) exponent = number > 1 (-) exponent = number < 1

48. Put in standard form 1.87 x 10–5 = 0.0000187 3.7 x 108 = 370,000,000 7.88 x 101 = 78.8 2.164 x 10–2 = 0.02164 Change to scientific notation 12,340 = 1.234 x 104 0.369 = 3.69 x 10–1 0.008 = 8 x 10–3 1,000,000,000 = 1 x 109 6.02 x 1023 = 602,000,000,000,000,000,000,000

49. EE EXP Using the Exponent Key

50. 6 6 6 6 6 1 1 0 0 0 0 0 0 0 x x y x EE EE EE y x 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 . . . . . How to type out 6.02 x 1023: How to type out 6.02 x 1023: The EE or EXP or E key means “times 10 to the…” not… WRONG! WRONG! or… and not… TOO MUCH WORK.