LABORATORY SAFETY

1. LABORATORY SAFETY Keep all books, backpacks, coats, etc. off of the lab benches No eating or drinking in the lab room Wear goggles and covered shoes at all times Know the location of the following safety equipment: Fire Extinguishers – next to all 3 exit doors Eye Washes – in the 2 back corners of the lab room 1A-1 (of 33)

2. Wash chemicals off of your skin with large amounts of water Clean all spills and breaks immediately Never use flames around flammable liquids (such as acetone) Lubricate glass when inserting into rubber stoppers Always pour Acid Into Water Waft to determine odors of chemicals Heat test tubes on a slant, without pointing them at people Dispose of hazardous chemicals in waste bottles 1A-2

3. LABORATORY EQUIPMENT Know the equipment on pages 6 and 7 of your lab manual Know the following glassware accuracies: volumetric flask pipet, buret graduated cylinder beaker, Erlenmeyer flask For accurate work : use pipets or burets For approximate work : use graduated cylinders For storing liquids : use beakers or Erlenmeyer flasks most accurate least accurate 1A-3

4. CHAPTER 1 – CHEMISTRY: AN INTRODUCTION CHEMISTRY – The study of materials and the changes they undergo 1A-4

5. CHAPTER 2 – MEASUREMENTS AND CALCULATIONS SCIENTIFIC NOTATION – The expression of a number as the product of a number between 1 and 10 and the appropriate power of 10 M  10n  number of places decimal point is moved  number between 1 and 10 1A-5

6. 365 4,387 58.33 3.65 × 102 0.0791 0.00320 1.62 7.91 × 10-2 3 ____ 64 0.046875 4.6875 × 10-2 1A-6

7. UNITS Science uses the International System of units (SI) based on the metric system Length Meter (m) Mass Gram (g) Volume Liter (L) ( = 39.37 inches) ( = 0.035274 ounces) ( = 1.060 quarts) 1A-7

8. 1 m = m 1 m = m 1 m = m METRIC PREFIXES Prefix Symbol Base Unit Multiplying Factor mega M 106 kilo k 103 BASE UNIT 100 deci d 10-1 centi c 10-2 milli m 10-3 micro μ 10-6 nano n 10-9 1A-8

9. 1 liter = 1 dm3 1 mL = 1 cm3 = 1 cc 1A-9

10. MEASUREMENT UNCERTAINTY UNCERTAINTY – The accepted error when making multiple measurements with a measuring device closest divisions: 1 cm You will have to estimate the number one decimal place past the closest divisions  The uncertainty with this ruler will be one decimal place past the “ones” column Measurements with this ruler will be written one decimal place past the “ones” column 1A-10

11. closest divisions: 1 cm You will have to estimate the number one decimal place past the closest divisions  The uncertainty with this ruler will be one decimal place past the “ones” column Measurements with this ruler will be written one decimal place past the “ones” column 1A-11

12. best estimate is 6.6 cm Manufacturers give the uncertainty for many types of graduated measuring devices If not, the uncertainty is estimated by taking the closest divisions and dividing by 2 uncertainty: 1 cm  2 = 0.5 cm 6.6  0.5 cm 1A-12

13. best estimate is 6.6 cm • SIGNIFICANT FIGURES – The digits recorded in a measurement • (all the certain digits plus one uncertain digit) 6.6 cm has 2 significant figures 1A-13

14. closest divisions: 0.1 cm You will have to estimate the number one decimal place past the “tenths” column 1A-14

15. best estimate is 6.55 cm uncertainty: 0.1 cm  2 = 0.05 cm 6.55  0.05 cm 6.55 cm has 3 significant figures 1A-15

16. closest divisions: estimate the: uncertainty: 1A-16

17. closest divisions: estimate the: uncertainty: 1A-17

18. closest divisions: estimate the: uncertainty: 1A-18

19. given uncertainites: readings: 0.03 mL 10.00 mL 1A-19

20. Significant figures are determined only for measurements , not for (1) Counted numbers (30 students enrolled) (2) Defined numbers (1 km = 103 m) (I hr = 60 min) 1A-20

21. RULES FOR COUNTING SIGNIFICANT FIGURES (1) All nonzero digits are significant 596 24.75 3,941 .876 3 4 4 3 (2) Zeros that start a number are not significant 0.021 0.0035 0.0908 0.467 2 2 3 3 1A-21

22. (3) Zeros that end a number without a decimal point are not significant 300 2,700 16.0 40.00 1 2 3 4 40 40. 40.0 40.00 1 2 3 4 uncertain in “tens” place uncertain in “ones” place uncertain in “tenths” place uncertain in “hundredths” place 1A-22

23. A non-significant zero can be made significant with a bar over it 300 _ 300 _ 300 300.0 1 2 3 4 1A-23

24. 12.3 12.370 0.00524 0.0010 600 23.00 3,019 43,100 1,600. 0.00313 19.027 0.07204 1A-24

25. When writing a measurement in scientific notation, only significant figures are shown • _ • 680 680 680.0 6.8 × 102 6.80 × 102 6.800 × 102 1A-25

26. OPERATIONS WITH MEASUREMENTS 1) ADDING AND SUBTRACTING MEASUREMENTS The answer’s last digit will be in the same place as the last digit in the least accurate measurement 20.63 mL + 6.6 mL ________________ 3 Accurate to the hundredths Accurate to the tenths 6 27.23 mL 27.2 mL 3 Must round to the tenths If the last digit removed is 0 to 4, do not round up ←Correct answer 1A-26

27. 1.84 g + 0.576 g 1.84 g + 0.576 g ________________ 4 Accurate to the hundredths Accurate to the thousandths 6 2.416 g 2.42 g 6 Must round to the hundredths If the last digit removed is 5 to 9, round up ← Correct answer 1A-27

28. 9 cm + 0.07 cm + 3.5 cm 1A-28

29. 32.3 m2 - 15.61 m2 1A-29

30. 2) MULTIPLYING AND DIVIDING MEASUREMENTS The number of sig fig’s in the answer will equal the number of sig fig’s in the measurement with the least number of sig fig’s Sig Fig’s: 3 4 Answer will have 3 sig fig’s 17.2 m x 5.042 m = 86.7224 m2 = 86.7 m2 ← Correct answer 1A-30

31. Sig Fig’s: 3 1 2 Answer will have 1 sig fig’s 2.41 cm x 0.003 cm x 0.25 cm = 0.0018075 cm3 = 0.002 cm3 ← Correct answer 1A-31

32. (2.1  103 kW)(3.65  102 h) 1A-32

33. 150. m 0.070 s 1A-33