LABORATORY SAFETY Keep all books, backpacks, coats, etc. off of the lab benches - PowerPoint Presentation

LABORATORY SAFETY Keep all books, backpacks, coats, etc. off of the lab benchesNo eating or drinking in the lab roomWear goggles, a lab coat, gloves, and covered shoes when working with chemicalsKnow the location of the following safety equipment: Fire Extinguisher – to the left of the white board in the front of the lab room Eye Wash – to the right of the white board in the front of the lab room Safety Shower – to the right of the white board in the front of the lab room 1A-1 (of 32) (1 – 1-12) (2 – 13-32 + 1-4 )

Wash chemicals off of your skin with large amounts of water Clean all spills and breaks immediatelyNever use flames around flammable liquids (such as acetone)Always pour Acid Into WaterWaft to determine odors of chemicalsHeat test tubes on a slant, and not at the very bottomDispose of hazardous chemicals in waste bottles1A-2

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

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

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

3.65 × 1024.387 × 103 5.833 × 10 1 365 4,387 58.33 7.91 × 10 -2 3.20 × 10 -3 1.62 × 10 0 0.0791 0.00320 1.62 1A-6

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

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 1 m = m 1 m = m 1 m = m John McClane 1A-8 Yippe - kai-ay, BUMF

1 liter = 1 dm 3 1 mL = 1 cm3 = 1 cc 1A-9

MAKING MEASUREMENTS best estimate is 6.7 cm The “6” is known accurately because the closest divisions are “ones” The “ 0.7” is estimated because there are no divisions for “tenths” When making a measurement, record every digit known accurately, and then one digit that is estimated Closest divisions: 1 cm each 1A-10

SIGNIFICANT FIGURES – The digits recorded in a measurement (all the certain digits plus one uncertain digit) best estimate is 6.7 cm 6.7 cm has 2 significant figures 1A-11

best estimate is 6.75 cmThe “6” and “0.7” are known accurately because the closest divisions are “tenths”The “0.05” is estimated because there are no divisions for “hundredths” Closest divisions: 0.1 cm each 1A-12

best estimate is 6.75 cm 6.75 cm has 3 significant figures 1A-13

closest divisions: estimated place:reading:significant figures:1 mL eachtenths place83.5 mL3 1A-14

closest divisions: estimated place:reading:significant figures:0.1 mL eachhundredths place2.65 mL3 1A-15

closest divisions: estimate the: reading:significant figures:1 mL eachtenths place54.0 mL3 1A-16

TOLERANCE – The accepted error when making multiple measurements with a measuring device Manufacturers give the tolerance for many types of graduated measuring devicesThe reading on a graduated measuring device should be to the same decimal place as the tolerance 1A-17

given tolerances: readings:significant figures: 0.03 mL10.00 mL 4 1A-18

Significant figures are determined only for measurements , not for (1) Counted numbers (28 students enrolled) (2) Defined numbers (1 km = 10 3 m) (I hr = 60 min) 1A-19

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-20

(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 1 2 3 4 40. 40.0 40.00 1A-21 uncertain in “ones” place uncertain in “tens” place uncertain in “tenths” place uncertain in “hundredths” place 40 ± 10 40. ± 1 40.0 ± 0.1 40.00 ± 0.01

A non-significant zero can be made significant with a bar over it 1 2 3 4 _ 300 _ 300 300.0 1A-22 300 300 ± 10 300 ± 1 300 ± 0.1 300 ± 100

12.3 12.370 0.00524 0.0010 3 5 3 2 600 23.00 3,019 43,100 1 4 4 3 1,600. 0.00313 19.027 0.07204 4 3 5 4 1A-23

When writing a measurement in scientific notation, only significant figures are shown _ 680 680 680.0 6.8 × 10 2 6.80 × 10 2 6.800 × 10 2 1A-24 2 3 4

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 _______________ Accurate to the hundredths Accurate to the tenths 27.23 mL 27.2 mL Must round to the tenths If the last digit removed is 0 to 4, do not round up ← Correct answer 3 6 OPERATIONS WITH MEASUREMENTS 3 1A-25

1.84 g + 0.576 g _______________Accurate to the hundredthsAccurate to the thousandths 2.416 g 2.42 g Must round to the hundredths If the last digit removed is 5 to 9, round up ← Correct answer 4 6 1.84 g + 0.576 g 6 1A-26

12.57 cm 13 cm 9 cm 0.07 cm + 3.5 cm _______________ Accurate to the ones Accurate to the hundredths Accurate to the tenths Must round to the ones ← Correct answer 9 7 9 cm + 0.07 cm + 3.5 cm 5 1A-27

32.3 m 2 - 15.61 m2 _______________Accurate to the tenthsAccurate to the hundredths 16.69 m 2 16.7 m 2 Must round to the tenths ← Correct answer 3 1 32.3 m 2 - 15.61 m 2 1A-28

= 867.224 m 2= 867 m2 ← Correct answer2) 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 17.2 m x 50.42 m Sig Fig’s: 3 4 Answer will have 3 sig fig’s 1A-29

= 0.0018075 cm 3= 0.002 cm3 ← Correct answer 2.41 cm x 0.003 cm x 0.25 cm Sig Fig’s: 1 2 Answer will have 1 sig fig 3 1A-30

(2.1  103 kW)(3.65  102 h)Sig Fig’s: 2 3 Answer will have 2 sig fig’s = 7.665  10 5 kWh = 7.7  10 5 kWh ← Correct answer 1A-31

150. m  0.070 sSig Fig’s: 3 2 Answer will have 2 sig fig’s = 2,142.857143 m/s = 2,100 m/s ← Correct answer 1A-32