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Unit 1: Observation, Measurement and Calculations

Unit 1: Observation, Measurement and Calculations. Cartoon courtesy of NearingZero.net. I. Introduction to Chemistry. A. How to Succeed in Chemistry. 1. Learn the ________ 2. ____ the illustrations 3. Review your notes _________ 4. Work as many problems as possible

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Unit 1: Observation, Measurement and Calculations

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  1. Unit 1:Observation, Measurement and Calculations Cartoon courtesy of NearingZero.net

  2. I. Introduction to Chemistry A. How to Succeed in Chemistry 1. Learn the ________ 2. ____the illustrations 3. Review your notes _________ 4. Work as many problems as possible 5. Do ____cram for exams. language Use frequently NOT

  3. B. What is Chemistry? 1. Chemistry is the study of the composition of “______” – (matter is anything with ____ and ____________), its composition, properties, and the ______ it undergoes. 2. Has a definite effect on __________- taste of foods, grades of gasoline, etc. 3. Living and nonliving things are made of ______. matter occupies space mass changes everyday life matter

  4. C2H5OH+3O2 2 CO2 + 3 H2O + Energy Reactants  Products

  5. C. Branches of Chemistry 1. Many major areas of study for specialization 2. Several career opportunities 3. Also used in many other jobs

  6. 1. Organic Chemistry a. Organic is the study of matter that contains ______. b. Organic chemists study the structure, function, _______, and identity of carbon compounds. c. Useful in petroleum industry,pharmaceuticals, ________. carbon synthesis polymers

  7. 2. Inorganic Chemistry a. Inorganic is the study of matter that does ____ contain carbon. b. _______ chemists study the structure, function, synthesis, and identity of non-carbon compounds c. Polymers, _________ NOT Inorganic Metallurgy

  8. 3. Biochemistry a. Biochemistry is the study of chemistry in _____ things. b. Cross between biology and ________. c. Pharmaceuticals and _______. living chemistry genetics

  9. 4. Physical Chemistry HONK if you passed p-chem a. Physical chemistry is the physics of chemistry… the _____ of matter b. Much of p-chem is ____________ c. Develop _________ ideas for new compounds forces computational theoretical

  10. 5. Analytical Chemistry a. Analytical chemistry is the study of high _______ measurement b. Find composition and ______ of chemicals c. ________, quality control, medical tests precision identity Forensics

  11. D. The Functions of Science the search for knowledge; facts using knowledge in a practical way pure science applied science

  12. Science attempts to establish ___________ ___________. cause-effect relationships

  13. 1. Pure Science ? a. The search for _____ about the natural world. facts • Driven by curiosity: the need to know, explore, conquer something new. • The goal in pure science is NOT to make money – but to understand.

  14. 2. Applied Science a. The practical _________ of scientific discoveries. application technology • b. Also known as “_________”

  15. E. Why Study Chemistry? 1. What benefits do each of the pictures represent in improving our lives? 2. Give examples in your daily life that involve use of chemistry, and things that do not? Figure 1.2, page 8

  16. Macroscopic F. Chemistry Far and Wide: 1. __________: objects seen with the unaided eye. 2. _________: objects seen only under magnification. 3. Chemists impact materials, ______, ________, __________, environment, and the study of the universe. Microscopic energy medicine agriculture

  17. Alchemists G. Thinking Like a Scientist: 1. __________ developed the tools and techniques for working with chemicals. 2. _________ helped transform chemistry from a science of observation to the science of measurement. 3. When scientists __________ and communicate, they increase the likelihood of a successful outcome. Lavoisier collaborate

  18. logical 4. Scientific Method: a. The scientific method is a ______, systematic approach to the solution of a scientific problem. b. Steps in the scientific method include making ____________, testing __________, and developing ________. hypotheses observations theories

  19. plan II. Problem Solving in Chemistry: NOTE: Effective problem solving always involves developing a ____ and then implementing that plan. NOTE:The steps for solving a numeric word problem are ________, _______________, and ________. analyze calculate / solve evaluate Shopping involves problem solving skills.

  20. A. Types of Observations and Measurements 1. We make _________ observations of reactions — changes in color and physical state. 2. We also make ______________________, which involve numbers. • i.e “hot vs. 97.9°C” qualitative quantitative measurements

  21. B. A General Procedure for Solving Problems 1. Read the problem carefully and make a list of the “knowns” and the ‘unknowns” 2. Look up all needed information NOTE: Your lecture notes will NOT have all of the needed information. 3 Work out a plan and, following your plan, obtain an answer by carrying out the required math. 4. Check over your work a. This is best done by estimating your answer b. Ask yourself: “Does the answer seem reasonable?”

  22. C. Useful Geometry Formulas A = s2 V = s3

  23. D. Uncertainty in Measurement NOTE: A digit that must be ________is called ________. A __________ always has some degree of uncertainty. uncertain estimated measurement

  24. 1. Why Is there Uncertainty? a. Measurements are performed with __________ b. No instrument can read to an ______number of decimal places instruments infinite Which of these balances has the greatest uncertainty in measurement?

  25. 2. Accuracy vs. Precision Accuracy a. _______ - how close a measurement is to the accepted value b. ________ - how close a series of measurements are to each other Precision ACCURATE = CORRECT PRECISE = CONSISTENT

  26. Precision and Accuracy Neither accurate nor precise Precise but not accurate Precise AND accurate

  27. E. Significant Figures precision a. Indicates ________ of a measurement. b. Recording Sig Figs • Sig figs in a measurement include the ______ digits plus ________________ one estimated digit known 2.35 cm

  28. 3. Rules for Counting Significant Figures - Details a. ______________ always count as significant figures. Nonzero integers 4 3456has__sig figs Leading zeros not b. ___________do ___ count as • significant figures. 3 0.0486has__sig figs

  29. Captive zeros c. ___________ always count as significant figures. 4 16.07has__sig figs Trailing zeros d. ___________ are significant only if the number contains a decimal point. 4 9.300has__sig figs

  30. 4. Sig Fig Practice #1 Calculate the correct number significant figures in each of the following: a. 1.0070 m  5 sig figs b. 17.10 kg  4 sig figs c. 100,890 L  5 sig figs d. 3.29 x 103 s  3 sig figs e. 0.0054 cm  2 sig figs f. 3,200,000  2 sig figs

  31. 5. Significant Figures • ____________ do not limit the # of sig figs in the answer. 1) _______ numbers: 12 students 2) Exact _________: 1 m = 100 cm b. “__” in any conversion: 1 in = 2.54 cm Exact Numbers Counting conversions 1

  32. 3 SF Significant Figures c. Calculating with Sig Figs 1) ____________- The # with the _____sig figs determines the # of sig figs in the answer. Multiply/Divide lowest (13.91g/cm3)(23.3cm3) = 324.103g 4 SF 3 SF 324 g

  33. 6. Sig Fig Practice #2 Calculation Calculator says: Answer 22.68 m2 a. 3.24 m x 7.0 m 23 m2 b. 100.0 g ÷ 23.7 cm3 4.22 g/cm3 4.219409283 g/cm3 c. 0.02 cm x 2.371 cm 0.05 cm2 0.04742 cm2 d. 710 m ÷ 3.0 s 236.6666667 m/s 240 m/s 5870 lb·ft e. 1818.2 lb x 3.23 ft 5872.786 lb·ft 0.358885017 g/mL 0.359 g/mL f. 1.030 g ÷ 2.87 mL

  34. Significant Figures 7. Add/Subtract - The # with the lowest ___________ determines the place of the last digit in the answer. decimal value **Least number of digits to the right of the decimal. 224 g + 130 g 354 g 3.75 mL + 4.1 mL 7.85 mL 3.75 mL + 4.1 mL 7.85 mL  350 g  7.9 mL

  35. 8. Sig Fig Practice #3 Calculation Calculator says: Answer 10.24 m a. 3.24 m + 7.0 m 10.2 m b. 100.0 g - 23.73 g 76.3 g 76.27 g c. 0.02 cm + 2.371 cm 2.39 cm 2.391 cm d. 713.1 L - 3.872 L 709.228 L 709.2 L 1821.6 lb e. 1818.2 lb + 3.37 lb 1821.57 lb 0.160 mL 0.16 mL f. 2.030 mL - 1.870 mL

  36. Procedure Show all measurements next to drawing of card (BE NEAT AND ORGANIZED!!) Show work and give both unrounded and rounded answers (Area and perimeter should each have 2 answers). Analyses and Conclusion Cross out #2 #3 refers to your rounded answers. Compare to the other lab group at your table. #4- Calculate the % error for the length and the width. Units should be in % for final answer General Put a box around each answer. Quick Lab 3.1

  37. F. Scientific Notation NOTE: In science, we deal with some very _____ numbers: large 1 mole = 602000000000000000000000 NOTE: In science, we deal with some very _____numbers: small Mass of an electron = 0.000000000000000000000000000000091 kg

  38. Imagine the difficulty of calculating the mass of 1 mole of electrons! 0.000000000000000000000000000000091 kg x 602000000000000000000000 ???????????????????????????????????

  39. . 2 5 0 0 0 0 0 0 0 0 9 7 6 5 4 3 2 1 8 decimal a. Step #1: Insert an understood ______ point b. Step #2: Decide where the decimal must end up so that ____ number is to its left one places c. Step #3: Count how many _____ you bounce the decimal point M x 10n d. Step #4: Re-write in the form ________

  40. M x 10n 2.5 x 109 exponent 2. The _______ is the number of places we moved the ______. decimal

  41. 0.0000579 1 2 3 4 5 Step #2: Decide where the decimal must end up so that one number is to its left Step #3: Count how many places you bounce the decimal point Step #4: Re-write in the form M x 10n

  42. M x 10n 5.79 x 10-5 negative 3. The exponent is _______ because the number we started with was ____ than 1. less

  43. EE EXP 4. Using the Exponent Keyon a Calculator

  44. 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: NOTE:EE or EXP means “times 10 to the…” Don’t do it like this… WRONG! WRONG! …or like this… …or like this: TOO MUCH WORK.

  45. NOTE: Also, know when to hit your (–) sign… …before the number, …after the number, …or either one.

  46. Type this calculation in like this: 1.2 x 105 2.8 x 1013 1 2 Calculator gives… 4.2857143 –09 1 8 3 2 5 or… 4.2857143 E–09 EE EE This is NOT written… 4.3–9 4.3 x 10–9 . . or 4.3 E –9 = Example: But instead is written…

  47. . Divide: (5.44 x 107) (8.1 x 104) . How to Use a Scientific Calculator 671.604938 5.44 8.1 54400000. 04 00 07 00 How to enter this on a calculator: . . 5.44 7 8.1 4 EE EE ENTER OR . . 5.44 7 8.1 4 EXP = EXP 671.6049383 rounded to 6.7 x 102 Davis, Metcalfe, Williams, Castka, Modern Chemistry, 1999, page 52

  48. = 6.525 x 10-9 report 6.5 x 10-9 (2 sig. figs.) = 5.3505 x 103 or 5350.5 report 5.35 x 103 (3 sig. figs.) = 9.86 x 10-4 report 9.86 x 10-4 (3 sig. figs.) = 2.904 x 1023 report 2.9 x 1023 (2 sig. figs.) = -3.07122 x 1016 report -3.1 x 1016 (2 sig. figs.)

  49. Significant Figures Review Measurement Number of significant figures it contains Measurement Number of significant figures it contains 25 g 0.030 kg 1.240560 x 106 mg 6 x 104 sec 246.31 g 20.06 cm 1.050 m 0.12 kg 1240560. cm 6000000 kg 6.00 x 106 kg 409 cm 29.200 cm 0.02500 g 2 2 7 1 5 4 4 2 7 1 3 3 5 4

  50. Number vs. Quantity • Quantity - number + unit UNITS MATTER!!

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