Chapter 1: Chemistry and You

1. Chapter 1: Chemistry and You Explain why a knowledge of chemistry is central to many human endeavors. List and describe the steps of the scientific method. Explain the basic safety rules that must be followed when working in the chem lab. Identify the metric units of measurement used in chemistry. Explain what causes uncertainty in measurements. Compare accuracy and precision. Explain how to use significant figures and scientific notation. Calculate percent error. Define density and explain how it is calculated. Explain how dimensional analysis and conversion factors are used to solve problems in chemistry.

2. Vocab • Chemistry • Scientific method • Observation • Hypothesis • Experiment • Conclusion • Natural law • Theory • Variable • Experimental control • Metric system • International System of Units (SI) • Base unit • Mass • Volume • Metric prefix • Precision • Accepted unit • Accuracy • Significant digit • Percent error • Density • Dimensional analysis • Conversion factor

3. Chapter 1: Chemistry and You • Look at the pic on p. 2 and read the caption • Name some of the basic chemical substances that make up your body. • Name some other chemical processes, besides digestion, that occur in your body. • Can you think of an important chemical reaction that occurs in plants and trees?

4. Section 1-1 What is Chemistry?

5. Chemistry in Action • Chemistry is a broad science that touches nearly every aspect of human life. • What are some ways chemistry affects the 2 careers mentioned in the section? • Examining a wetlands habitat • Preserving historical artifacts

6. The Central Science • Chemistry has been called the central science b/c it overlaps so many sciences • Careers that use chemistry • Hair stylists • Construction • Biologists • What others? • Possible chemistry careers • Police departments (CSI) • Perfume companies • Research chemists

7. Why Study Chemistry? • It is involved in many aspects of life • Helps you to understand the world around you

8. Cleaning Priceless Art • Read the “Connection” box on p. 6 • What occupation is using chemistry? • What did they do to clean the art? • Why are some people upset about their actions?

9. Section 1-2 The Scientific Method

10. The Scientific Method Observation Question Hypothesis Experiment Conclusion • A way of answering questions about the world we live in • Oscar Has Extremely Colorful T-Shirts Theory (Model) Natural Law Theory modified as needed Prediction Experiment

11. Observation • Seeing a problem or asking a question that you cannot answer • Always leads to a question

12. Hypothesis • An educated guess • Usually asked in a “cause-effect” statement • Must be able to test the hypothesis

13. Experiment • A test of the hypothesis • Data will be collected and analyzed • Must have 1 variable and at least 1 constant • Variable – the particular factor being tested

14. Conclusion • The result of the analyzed data • May agree or disagree with your hypothesis

15. Theory • Answers the original question as well as any others formed during the process • Predicts the results of further experiments

16. Scientific/Natural Law • Describes how nature behaves but not why

17. 1-2 Section Review • On looseleaf to turn in, page 13 (1-5)

18. Bikini Bottom Experiments • With your small group, complete the SpongeBob worksheet • SpongeBob Scientific Method.pdf

19. Section 1-3 Safety in the Lab

20. Section 1-4 Units of Measurement

21. Units of Measurement • Measurement: always includes a number and unit • If someone is 7 feet tall, “7” is the number and “feet” is the unit • Saying someone is 7 does not tell you enough info • They could be 7 yrs old, 7 feet tall, 7 inches tall, … • Feet and inches are part of the English system of measurement • In science, we use the Metric system • All scientists, no matter their country or language, use the metric system

22. United States, Liberia, and Burma

23. International System of Units • SI units used by all scientists around the world • Based on 7 metric units called base units • Length meter (m) • Mass kilogram (kg) • Time second (s) • Count/Quantity mole (mol) • Temperature Kelvin (K) • Electric Current ampere (A) • Luminous Intensity candela (cd)

24. Derived Units Area square meter (m2) Volume cubic meter (m3) Force Newton (N) Pressure Pascal (Pa) Energy joule ( J ) Power watt (W) Voltage volt (V) Frequency hertz (Hz) Electric charge coulomb (C)

25. Units • Science is a process, not a collection of rules • The most frequently used units in class that differ than SI: • Temperature - Celsius (˚C) • Volume – liter (L) • Pressure – atmosphere (atm) millimeters of mercury (mmHg) • Energy – calorie (cal)

26. Commonly used units • Length • A dime is 1 mm thick • A quarter is 2.5 cm in diameter • Average height of a man is 1.8 m • Mass • A nickel has a mass of 5 g • A 120 lb woman has a mass of about 55 kg • Volume • A 20 oz can of soda has a volume of 360 mL • A ½ gallon of milk is equal to 2 L

27. Metric Prefixes • KingHenry Died by drinking chocolate milk Base units include meter, liter, second, gram

28. How to Use Prefixes kilo- hecto- deca- Base units deci- centi- milli-

29. Example How many millimeters are in a meter? 1 meter = mm 1 meter = 1000 mm kilo- hecto- deca- base units deci- centi- milli-

30. Practice Problems • Convert a volume of 16 deciliters into liters • 1.6 L • Convert 1.45 meters into centimeters • 145 cm • Convert a volume of 8 deciliters into liters • 0.8 L • Is 5 centimeters longer or shorter than 8 millimeters? Explain. • 5 cm is longer than 8 mm b/c 0.05 m is greater than 0.008m

31. Metric Mania Worksheet

32. Section 1-5 Uncertainty in Measurement

33. Making Measurements • When making a measurement, write down everything given to you with one uncertain estimated number • 5.1 inches is easy to spot but we still need 1 uncertain number • My estimation = 5.12 inches • Measurements are uncertain b/c: • Measuring instruments are never completely free of flaws • Measuring always involves some estimation

34. Reliability in Measurement • Precision: the same result is given over and over under the same conditions • Accuracy: the result is close to a reliable standard • Accepted value: the reliable standard High Precision High Accuracy

35. Section 1-6 Working with Numbers

36. Working with numbers • Measurements are rarely used just by themselves. • Usually used in some form of mathematics (+, -, x, or ÷) • Produces values of mass, temperature, volume, etc.

37. Significant Figures (Digits) • The certain digits and the estimated digit of a measurement • Example: In the # 31.7, there are 3 sig figs • The 3 and 1 are certain digits while the 7 is the uncertain digit

38. Rules for Sig Figs • Nonzero #: any number that is not a zero • 1, 2, 3, 4, 5, 6, 7, 8, or 9 • Zeros • Never count “leading zeros” • 0023  only count the 2 and 3 • 0.054  only count the 5 and 4 • Always count “captive” or “sandwiched” zeros • 303  count the 3, 0, and 3 • “Trailing zeros”: zeros to the right • Only count if used with a decimal point • 5400  only count the 5 and 4 • 5.400  count the 5, 4, 0, and 0

39. Example • How many sig figs are in 0.057 010 g? • Nonzero numbers: • 0.057 010 • Captive zeros • 0.057 010 • Trailing zeros when there is a decimal • 0.057 010 • Final Answer • 0.057 010 • 5 significant figures

40. Practice Problems • How many sig figs in the following numbers? • 0.002 6701 m • 5 sig figs 0.002 6701 • 19.0550 kg • 6 sig figs 19.0550 • 3500 V • 2 sig figs 3500 • 1 809 000 L • 4 sig figs 1 809 000 • 95 600 m • 3 sig figs 95 600 • 520 mL • 2 sig figs 520 • 0.0102 ms • 3 sig figs 0.0102

41. Sig Fig Practice Wkst

42. Significant Figures in Calculations • Multiplying and Dividing • The answer will have the same # of sig figs as the measurement with the smallest # of sig figs • Volume = 3.052 m x 2.10 m x 0.75 m (4 sig figs) (3 sig figs) (2 sig figs) = 4.8069 m3 = 4.8 m3

43. Sig Figs in Calculations • Adding and Subtracting • The answer will have the same # of decimal places as the measurement with the smallest # of decimal places • 951.0 g 1407 g 23.911 g + 158.18 g 2540.091 g • Since there aren’t any decimals in 1407, our answer will not have decimals • Final answer = 2540 g

44. Practice Problems • 6.15 m x 4.026 m = • 24.7599 m2 = 24.8 m2 • 1.45 m x 1.355 m x 2.03 m = • 3.9884425 m3 = 3.99 m3 • 0.3287 g + 45.2 g = • 45.5287 g = 45.5 g • 0.258 mL ÷ 0.361 05 mL = • 0.71458246 mL = 0.715 mL

45. More Practice Worksheet

46. Scientific Notation • In science we work w/ very large and very small #s • For example: • 1 drop of water contains = 1,700,000,000,000,000,000,000 molecules • The mass of 1 proton = 0.000 000 000 000 000 000 000 000 001 672 62 kg

47. Scientific Notaion • To make it easier for ourselves, we use scientific notation • 1 drop of water contains = 1,700,000,000,000,000,000,000 molecules • 1 drop of water contains = 1.7 x 1021 • The mass of 1 proton = 0.000 000 000 000 000 000 000 000 001 672 62 kg • The mass of 1 proton = 1.67262 x 10-21

48. How to make # into scientific notation • Write 1700 in scientific notation • Write down the full number • 1700 • Move the decimal until it is right after the first 1-10 number • 1700  1700.  1.700 • Write down this new number without the zeros • 1.7 • Place “x 10” after this number • 1.7 x 10 • Count how many times you had to move the decimal and place that number after the 10 as an exponent • If you move to the right = negative exponent • If you move to the left = positive exponent • 1.7 x 103

49. Examples • 37 700 • 3.77 x 104 • 1 024 000 • 1.024 x 106 • 0.000 000 003 901 • 3.901 x 10-9 • 8960 • 8.96 x 103 • 0.000 23 • 2.3 x 10-4

50. Percents • Data will often be given as a percent • If it is a fraction, just divide and multiply by 100 • Ex: 900 million kilograms of plastic soft drink bottles are produced each year. 180 million kilograms of them are recycled. 180 million kilograms 900 million kilograms = 0.2 x 100% = 20%