Chapter 2 Analyzing Data. Chapter 2 Introduction 2.1 Units & Measurements2.1 Units & Measurements 2.2 Scientific Notation & Dimensional Analysis2.2 Scientific

Chapter 2Chapter 2

Analyzing DataAnalyzing Data

Chapter 2 IntroductionChapter 2 Introduction

• 2.1 Units & Measurements2.1 Units & Measurements

• 2.2 Scientific Notation & 2.2 Scientific Notation & Dimensional AnalysisDimensional Analysis– ““Factor-Label” Method a.k.a. Factor-Label” Method a.k.a.

Conversion Factors or Dimensional Conversion Factors or Dimensional AnalysisAnalysis

• 2.3 Uncertainty in Data2.3 Uncertainty in Data– Sig Figs, Sig DigsSig Figs, Sig Digs

Chapter 2 Learning TargetsChapter 2 Learning TargetsBy the end of Chapter 2 I am able to…By the end of Chapter 2 I am able to… Identify the SI base units of Identify the SI base units of

measurements for mass, time, length, measurements for mass, time, length, temperature & volume (2.1)temperature & volume (2.1)

Distinguish between qualitative & Distinguish between qualitative & quantitative observations and give quantitative observations and give examples of each. (2.1)examples of each. (2.1)

Explain the meanings of the SI prefixes Explain the meanings of the SI prefixes (2.1)(2.1)

Compare & contrast mass and weight Compare & contrast mass and weight (2.1)(2.1)

State the derived units used to represent State the derived units used to represent speed, area & density. (2.1)speed, area & density. (2.1)

Analyze a problem, solve for an unknown Analyze a problem, solve for an unknown and evaluate my answer (2.1)and evaluate my answer (2.1)

Chapter 2 Learning TargetsChapter 2 Learning Targets

Express numbers in scientific notation Express numbers in scientific notation (2.2)(2.2)

Convert between units using dimensional Convert between units using dimensional analysis/factor-label method (2.2)analysis/factor-label method (2.2)

Define & compare accuracy & precision Define & compare accuracy & precision (2.3)(2.3)

Describe the accuracy of experimental Describe the accuracy of experimental data using error & percent error (2.3)data using error & percent error (2.3)

Apply the rules of “Sig Figs” to express Apply the rules of “Sig Figs” to express uncertainty in measured & calculated uncertainty in measured & calculated values (2.3)values (2.3)

2.1 Units & Measurements 2.1 Units & Measurements Learning TargetsLearning Targets Identify the SI base units of measurements for Identify the SI base units of measurements for

mass, time, length, temperature & volume (2.1)mass, time, length, temperature & volume (2.1) Distinguish between qualitative & quantitative Distinguish between qualitative & quantitative

observations and give examples of each. (2.1)observations and give examples of each. (2.1) Explain the meanings of the SI prefixes (2.1)Explain the meanings of the SI prefixes (2.1) Compare & contrast mass and weight (2.1)Compare & contrast mass and weight (2.1) State the derived units used to represent speed, State the derived units used to represent speed,

area & density. (2.1)area & density. (2.1) Analyze a problem, solve for an unknown and Analyze a problem, solve for an unknown and

evaluate my answer (2.1)evaluate my answer (2.1)

2.1 Units & Measurements2.1 Units & Measurements

• Système Internationale d'Unités (SI) Système Internationale d'Unités (SI) is an internationally agreed upon is an internationally agreed upon system of measurements.system of measurements.

• Chemistry involves both measuring Chemistry involves both measuring and calculatingand calculating

• Two types of observations in Two types of observations in sciencescience– Qualitative (no measurements, no Qualitative (no measurements, no

numbers)numbers)– Quantitative (actual measurements)Quantitative (actual measurements)


• There are 7 base There are 7 base units in SIunits in SI

• Measurements Measurements based on an object based on an object or event (a physical or event (a physical standard). standard).

• See p. 33 in text.See p. 33 in text.• YOU NEED TO YOU NEED TO

KNOW THESE!KNOW THESE!


• To better To better describe the describe the range of range of possible possible measurements, measurements, scientists add scientists add prefixes to base prefixes to base unitsunits

• Based on Based on factors of 10 – factors of 10 – metric systemmetric system

** KNOW THESE… p 33 in text** KNOW THESE… p 33 in text


• Mass vs. WeightMass vs. Weight– WeightWeight is a measure of force of gravity is a measure of force of gravity

between two objects (wt. changes between two objects (wt. changes w/respect to gravity)w/respect to gravity)• Scales are for weighingScales are for weighing

– MassMass is a measure of the amount of is a measure of the amount of matter an object containsmatter an object contains• A balance is used for finding massA balance is used for finding mass• The SI unit for mass is the Kilogram (kg)The SI unit for mass is the Kilogram (kg)

The Physical Standard for The Physical Standard for Mass (FYI…)Mass (FYI…)• The international The international

prototype of the prototype of the kilogram is inside kilogram is inside three nested bell three nested bell jars at the Bureau jars at the Bureau International des International des Poids et Mesures Poids et Mesures in Paris.in Paris.

http://www.npr.org/templates/story/story.php?storyId=112003322

http://www.npr.org/templates/story/story.php?storyId=112003322

In search of a new Standard…

• Physicist Richard Steiner adjusts the watt balance. This extremely sensitive scale can detect changes as small as ten-billionths of a kilogram.


• Temperature: quantitative Temperature: quantitative measurement of the average kinetic measurement of the average kinetic energy of the particles w/in an energy of the particles w/in an object.object.

• A thermometer is used to measure A thermometer is used to measure temperaturetemperature

• Three temperature scales:Three temperature scales:– Fahrenheit, Celsius, KelvinFahrenheit, Celsius, Kelvin

• SI base unit - KelvinSI base unit - Kelvin


• Kelvin scale developed by William Kelvin scale developed by William Thomson (a.k.a. Lord Kelvin)Thomson (a.k.a. Lord Kelvin)

• Zero Kelvin is the point at which all Zero Kelvin is the point at which all molecular motion stops – “Absolute Zero”molecular motion stops – “Absolute Zero”

• The size of the Celsius degree (The size of the Celsius degree (ooC) is the C) is the same as a Kelvin (K)same as a Kelvin (K)

• To convert between the two:To convert between the two:K K C -273 C -273C C K +273 K +273Water boils at 100 Water boils at 100 ooC, to convert to Kelvin add C, to convert to Kelvin add

273. What is water’s BP in K?273. What is water’s BP in K?373 K373 K


• Derived Units: combination of base Derived Units: combination of base unitsunits

• Volume – SI unit is cubic meter (mVolume – SI unit is cubic meter (m33))– Usually the liter (L) is usedUsually the liter (L) is used– 1 L equals 1 dm1 L equals 1 dm33

– For laboratory use the cubic centimeter For laboratory use the cubic centimeter is often used (cmis often used (cm33 or cc) or cc)

– 1 cm1 cm33 = 1 mL (See Figure 2.4 p. 36) = 1 mL (See Figure 2.4 p. 36)

The three cubes show volume relationships The three cubes show volume relationships between mbetween m33 dm dm33 & cm & cm33. as you move from . as you move from left to right, the volume of each cube gets left to right, the volume of each cube gets 10 x 10 x 10, or 1000 (1010 x 10 x 10, or 1000 (1033) times smaller.) times smaller.

Figure 2.4 p. 36


• Derived Units… continuedDerived Units… continued

• Density – a physical property of Density – a physical property of matter matter – defined as amount of mass per unit defined as amount of mass per unit

volume (density = mass/volume)volume (density = mass/volume)

Common units:Common units:– g/cmg/cm3 3 for solids for solids – g/ml for liquids & gases g/ml for liquids & gases

ApplicationApplicationQuestion:Question: 116 g of sunflower oil is used in a recipe. The density 116 g of sunflower oil is used in a recipe. The density

of the oil is 0.925 g/ml. What is the volume of the sunflower oil of the oil is 0.925 g/ml. What is the volume of the sunflower oil in ml?in ml?

What are you being asked to solve for?What are you being asked to solve for?volume of sunflower oilvolume of sunflower oil

What do you know, what are you given?What do you know, what are you given?Density = mass/volumeDensity = mass/volumeDensity = 0.925 g/mlDensity = 0.925 g/mlMassMass = 116 g= 116 g

What is the unknown?What is the unknown? volumevolume

Write the equation and isolate the unknown factor.Write the equation and isolate the unknown factor.density = mass/density = mass/volumevolumerearrange to solve for unknown: rearrange to solve for unknown: volumevolume = =

mass/densitymass/densitySubstitute known quantities into equation & solve.Substitute known quantities into equation & solve.

volume = 116g/0.925g/mlvolume = 116g/0.925g/mlvolume = 125 mlvolume = 125 ml

2.1 HW problems

• #2-6 (p.38-39) , #66-67 (p. 62)

• Due :– Next class

2.2 Scientific Notation & 2.2 Scientific Notation & Dimensional Analysis Dimensional Analysis Learning TargetsLearning Targets

Express numbers in scientific Express numbers in scientific notation (2.2)notation (2.2)

Convert between units using Convert between units using dimensional analysis/factor-label dimensional analysis/factor-label method (2.2)method (2.2)

2.2 Scientific Notation & 2.2 Scientific Notation & Dimensional AnalysisDimensional Analysis• Scientific notation used for short-handing Scientific notation used for short-handing

very large and very small measurements.very large and very small measurements.

• Very large number - the number of atoms Very large number - the number of atoms in a sample might be something like in a sample might be something like

124,500,000,000,000 atoms.124,500,000,000,000 atoms.• Very small number - the size of an Very small number - the size of an

molecule in meters might be something molecule in meters might be something

like like 0.0000000000238 meters0.0000000000238 meters..

2.2 Scientific Notation & 2.2 Scientific Notation & Dimensional AnalysisDimensional Analysis• The number of places moved equals the The number of places moved equals the

value of the exponent. value of the exponent.

• The exponent is positive when the The exponent is positive when the decimal moves to the left and negative decimal moves to the left and negative when the decimal moves to the right.when the decimal moves to the right.

• Example:Example:

800 = 8.0 800 = 8.0 10 1022

0.0000343 = 3.43 0.0000343 = 3.43 10 10–5–5

CoefficientCoefficient

ExponentExponent

2.2 Application2.2 Application• Question:Question: Each cell in the human body Each cell in the human body

contains a complete genome which is contains a complete genome which is composed of base pairs. Each base composed of base pairs. Each base pair is 0.000,000,034m in length. There pair is 0.000,000,034m in length. There are 6,000,000,000 base pairs in each are 6,000,000,000 base pairs in each human cell. Change the above human cell. Change the above information into scientific notation.information into scientific notation.a.) 3.4 x 10a.) 3.4 x 10-8-8 m mb.) 6 x 10b.) 6 x 1099 base pairs base pairs

2.2 Scientific Notation & 2.2 Scientific Notation & Dimensional AnalysisDimensional Analysis

• Addition & Subtraction of numbers in Addition & Subtraction of numbers in scientific notation:scientific notation:– Exponents must be the same.Exponents must be the same.– Add or subtract coefficients.Add or subtract coefficients.

(7.35 x 10(7.35 x 1022 m) + (2.43 x 10 m) + (2.43 x 1022 m) = 9.78 x 10 m) = 9.78 x 1022 m m

Application

• Add 3.5 x 10Add 3.5 x 1033 m to 6.8 x 10 m to 6.8 x 1033 m m

(3.5 x 10(3.5 x 1033) + (6.8 x 10) + (6.8 x 1033) = 10.3 x 10) = 10.3 x 1033mm

Why???Why??? Answer must be 1.03 x 10 Answer must be 1.03 x 1044 because proper scientific notation because proper scientific notation states that you must have states that you must have oneone whole whole number to the left of the decimalnumber to the left of the decimal

NONO, you , you can’t write it can’t write it like this!like this!


• What if the exponents are What if the exponents are NOT NOT the same?the same?– Rewrite values with the same exponent.Rewrite values with the same exponent.– Example: Consider amounts of energy produced by Example: Consider amounts of energy produced by

renewable energy sources in the U.S. in 2004:renewable energy sources in the U.S. in 2004:• HydroelectricHydroelectric 2.840 x 102.840 x 1018 18 JJ• BiomassBiomass 3.146 x 103.146 x 1018 18 JJ• GeothermalGeothermal 3.60 x10 3.60 x1017 17 J J • WindWind 1.50 x 10 1.50 x 1017 17 JJ• SolarSolar 6.9 x 10 6.9 x 1016 16 JJ

What is the Total ? What is the Total ?

0.360 x 100.360 x 101818 J J

0.150 x 100.150 x 101818 J J

0.069 x 100.069 x 1018 18 JJ

6.565 x 106.565 x 101818 J J

Application

• Subtract 7.9 x 10Subtract 7.9 x 1022 km from 1.0 x 10 km from 1.0 x 1033 km km

(1.0 x 10(1.0 x 1033) – (0.79 x 10) – (0.79 x 1033)) ==

Remember you must write as 2.1 x 10Remember you must write as 2.1 x 102 2

(one whole number to the left of the (one whole number to the left of the decimal!!)decimal!!)

NONO, you , you can’t write it can’t write it like this!like this!

Move decimal place to the Left to make exponents the same, 103

0.21 x 100.21 x 1033


• Multiplication and division, exponents do NOT Multiplication and division, exponents do NOT need to be the same:need to be the same:– To multiply, multiply the coefficients, then add the To multiply, multiply the coefficients, then add the

exponents.exponents.(4.6 x 10(4.6 x 102323 atoms) (2x10 atoms) (2x10-23-23 g/atom) = g/atom) =

– To divide, divide the coefficients, then subtract the To divide, divide the coefficients, then subtract the exponent of the divisor from the exponent of the exponent of the divisor from the exponent of the dividend.dividend.

(9 x 10(9 x 1088) / (3 x 10) / (3 x 10-4-4))

Divide coefficients: 9/3 = 3Divide coefficients: 9/3 = 3

Subtract the exponents: 8 – (-4) = 8+4 = 12Subtract the exponents: 8 – (-4) = 8+4 = 12

Combine the parts: 3 x 10Combine the parts: 3 x 101212

9.2 x 109.2 x 1000 g = 9.2 g g = 9.2 g

Math Skill ReviewMath Skill Review

• Can you multiply these fractions? Can you multiply these fractions? Complete the following in your Complete the following in your notebook. Remember… MATH IN notebook. Remember… MATH IN PENCIL! PENCIL!

1.1. 2/3 x 5/72/3 x 5/72.2. 2/3 x 3/92/3 x 3/93.3. a/b x c/da/b x c/d4.4. aa22/b x b/b x b33/a/a5.5. 5 x 2/155 x 2/15


• ““Factor-Label Method” (Dimensional Factor-Label Method” (Dimensional Analysis & Conversion factors – book Analysis & Conversion factors – book name)name)

• Problem solving consists of three Problem solving consists of three parts:parts:

Known Known Conversion Factor Conversion Factor Desired Desired

AnswerAnswer

2.2 Scientific Notation & 2.2 Scientific Notation & Dimensional AnalysisDimensional Analysis• Conversion factors are ratios with a Conversion factors are ratios with a

value equal to onevalue equal to one• Example: $1 = 4 quartersExample: $1 = 4 quarters

1km = 1000m1km = 1000m• The ratios are written as follows:The ratios are written as follows:

$1 and 4 quarters$1 and 4 quarters 4 quarters $1 4 quarters $1

1 km1 km and and 1000 m1000 m 1000 m 1 km1000 m 1 km

2.2 Application2.2 Application

• An object is traveling at a speed of 7500 An object is traveling at a speed of 7500 centimeters per second. Convert the value to centimeters per second. Convert the value to kilometers per minute.kilometers per minute. Known: 7500 cm /sec Known: 7500 cm /sec Desired: ? km/minDesired: ? km/min

• What relationships are known between cm & What relationships are known between cm & km? Between sec & min? Write them downkm? Between sec & min? Write them down 100 cm = 1m; 1000 m = 1 km; 60 s = 1 min100 cm = 1m; 1000 m = 1 km; 60 s = 1 min

• Use these relationships as ratios in such a way Use these relationships as ratios in such a way that s, cm, & m all divide out:that s, cm, & m all divide out:

• km =km = minmin

Open Note Quiz

1.1. How many seconds in a class at How many seconds in a class at SKHS? Class periods are 98 SKHS? Class periods are 98 minutes.minutes.

2.2. Convert 78 seconds to hoursConvert 78 seconds to hours3.3. Convert 2.5 x 10Convert 2.5 x 1066 g to kg g to kg4.4. Convert 37.5g/ml to kg/LConvert 37.5g/ml to kg/L5.5. Convert 7.56 mmConvert 7.56 mm33/s to dm/s to dm33/min/min6.6. Convert 9.06 km/hr to m/sConvert 9.06 km/hr to m/s

2.2 HW – Due Next Class2.2 HW – Due Next Class

• #11-16 (p. 41-43)

• #19-20 (p. 45)

• #25 (p. 46)

• #76-80 (p. 62)

2.3 Uncertainty in Data Learning TargetsDefine & compare accuracy & Define & compare accuracy &

precision (2.3)precision (2.3)Describe the accuracy of Describe the accuracy of

experimental data using error & experimental data using error & percent error (2.3)percent error (2.3)

Apply the rules of “Sig Figs” to Apply the rules of “Sig Figs” to express uncertainty in measured & express uncertainty in measured & calculated values (2.3)calculated values (2.3)

2.3 Uncertainty in Data

• Accuracy & PrecisionAccuracy & Precision– AccuracyAccuracy refers to how close a refers to how close a

measured value is to an accepted measured value is to an accepted valuevalue

– PrecisionPrecision refers to how close refers to how close measurements are to one another.measurements are to one another.


Figure 2.10 on p. 47Figure 2.10 on p. 47

2.3 Uncertainty in Data Application

• Open your books and consider the data table, p. 48.

2.3 Uncertainty in Data Application - continued

• Students were asked to determine the density of an unknown white powder.

• Each student measured the volume and mass of three samples.

• They calculated the densities and averaged the three.

2.3 Uncertainty in Data Application - continued• Which student collected the most

accurate data?• Student A• Why?

– closest to the accepted value.

• Who collected the most precise data?• Student C• Why?• closest to one another.


• Error & Percent ErrorError & Percent Error– Error Error is defined as the difference is defined as the difference

between an experimental value (values between an experimental value (values measured during an experiment) and measured during an experiment) and an accepted valuean accepted value

– Error Equation:Error Equation:Error = experimental value – accepted valueError = experimental value – accepted value

Absolute valueAbsolute value… only concerned about how … only concerned about how far away from the target you were, so sign far away from the target you were, so sign doesn’t matterdoesn’t matter

2.3 Uncertainty in Data2.3 Uncertainty in Data

• Error & Percent Error (cont…)Error & Percent Error (cont…)– Percent Error Percent Error expresses error as a expresses error as a

percentage of the accepted value.percentage of the accepted value.– Percent Error Equation:Percent Error Equation:

Absolute value is used because Absolute value is used because only the size of the error only the size of the error matters; it does not matter matters; it does not matter whether the experimental value whether the experimental value is larger or smaller than the is larger or smaller than the accepted value.accepted value.

2.3 Application – do this in 2.3 Application – do this in your notebook as part of your your notebook as part of your notesnotes

• The melting point of paradichlorobenzene is The melting point of paradichlorobenzene is 5353ooC. In a laboratory activity two students C. In a laboratory activity two students tried to verify this value.tried to verify this value.

Student #1 records: 51.5Student #1 records: 51.5ooC, 53.5C, 53.5ooC, 55.0C, 55.0ooC, C, 52.352.3ooC, and 54.2C, and 54.2ooCC

Student #2 records: 52.3Student #2 records: 52.3ooC, 53.2C, 53.2ooC, 54.0C, 54.0ooC, C, 52.552.5ooC, and 53.5C, and 53.5ooCC

a.a. Calculate the average value for the two Calculate the average value for the two studentsstudents

b.b. Calculate the percent error for each studentCalculate the percent error for each studentc.c. Which of the students is most precise? Which of the students is most precise?

Accurate? Explain.Accurate? Explain.

Calculate the average value for Calculate the average value for the two studentsthe two students

Student #1: 51.5Student #1: 51.5ooC + 53.5C + 53.5ooC + 55.0C + 55.0ooC + C + 52.352.3ooC + 54.2C + 54.2ooC = 266.5/5 = C = 266.5/5 = 53.353.3ooCC

Student #2 : 52.3Student #2 : 52.3ooC + 53.2C + 53.2ooC + 54.0C + 54.0ooC + C + 52.552.5ooC + 53.5C + 53.5ooC = C = 53.153.1ooCC

Calculate the percent error Calculate the percent error for each studentfor each student

• Student #1:Student #1:Percent error =Percent error =

• Student #2:Student #2:Percent error =Percent error =

(53.3oC - 53.0oC) X100 = 0.566 % error

53.0oC

(53.153.1ooC - 53.0C - 53.0ooC) X100 = C) X100 = 0.189 % error0.189 % error

53.053.0ooCC

Which of the students is Which of the students is most precise? Accurate? most precise? Accurate? Explain.Explain.

• Student 2 is the most precise with a Student 2 is the most precise with a range of values from 52.3 to 54.0. range of values from 52.3 to 54.0.

• Student 2 is also most accurate with Student 2 is also most accurate with a 0.189 % error.a 0.189 % error.


• Significant FiguresSignificant Figures: include all known : include all known digits plus one estimated digit.digits plus one estimated digit.

• Often precision is limited by the tools Often precision is limited by the tools available.available.

Figure 2.12 p. 50 The Figure 2.12 p. 50 The markings on the ruler markings on the ruler represent the known represent the known digits plus the estimated digits plus the estimated digit. The measure is digit. The measure is 5.23 cm. What is the 5.23 cm. What is the estimated digit if the estimated digit if the length of the object fell length of the object fell directly on the 5 cm directly on the 5 cm mark?mark?

5.00 cm

2.3 Uncertainty in Data2.3 Uncertainty in Data• Rules for Significant Figures:Rules for Significant Figures:

–Rule 1:Rule 1: Nonzero numbers are always Nonzero numbers are always significant.significant.•Example: 72.3 gExample: 72.3 g• 9.4567 9.4567

–Rule 2:Rule 2: Zeros between nonzero numbers Zeros between nonzero numbers are always significant.are always significant.•Example: 60.5 gExample: 60.5 g• 5005.055005.05

–Rule 3:Rule 3: All All finalfinal zeros to the right of the zeros to the right of the decimal are significant.decimal are significant.•Example: 6.2000Example: 6.2000

How many sig figs?How many sig figs? 33


How many sig figs?How many sig figs? 33How many sig figs?How many sig figs? 66



• Rules for Significant Figures:Rules for Significant Figures:– Rule 4:Rule 4: Placeholder zeros are not Placeholder zeros are not

significant. To remove placeholder zeros, significant. To remove placeholder zeros, rewrite the number in scientific notation.rewrite the number in scientific notation.• Example: 0.0253g and 4320 (3 sig figs each) Example: 0.0253g and 4320 (3 sig figs each)

Rewritten in Scientific notation: Rewritten in Scientific notation:

2.53 x 102.53 x 10-2-2 4.32 x 104.32 x 1033

0.0006010.000601

5000050000



6.01 x 106.01 x 10-4-4

5 x 105 x 1044


• Rules for Significant Figures:Rules for Significant Figures:–Rule #5: Counting numbers Rule #5: Counting numbers

and defined constants have an and defined constants have an infinite number of significant infinite number of significant figures.figures.

–Example: 6 moleculesExample: 6 molecules

60s = 1 min60s = 1 min


Examples using the Examples using the 4 Rules:4 Rules:

54655465

0.607500.60750

0.0200200.020020

500.0500.0

300300

How many Sig FigsHow many Sig Figs

4 – Rule #14 – Rule #1

5 – Rules #2 & 35 – Rules #2 & 3

5 – Rules #2 & 35 – Rules #2 & 3

4 – Rules #2 & 34 – Rules #2 & 3

1 – Rule #41 – Rule #4


– What happens when your calculator gives you a What happens when your calculator gives you a funky number, how do you know how many sig funky number, how do you know how many sig figs to report in your answer?figs to report in your answer?

– Rule 6:Rule 6: Addition & SubtractionAddition & Subtraction, answer will have , answer will have the number of sig figs from the number with the the number of sig figs from the number with the least amount of decimal places in the problem.least amount of decimal places in the problem.

Example: Example:

10.2110.21

0.20.2

+ 256+ 256

266.41266.41

So… my answer should So… my answer should have 0 decimal placeshave 0 decimal places

Decimal PlacesDecimal Places

22

11

00

266 266


– Rule 7: Rule 7: Multiplication & DivisionMultiplication & Division The The answer will have the number of sig figs from answer will have the number of sig figs from the number with the least amount of sig figs.the number with the least amount of sig figs.

Example:Example:

4675 x 625 = ________4675 x 625 = ________

Which has the least # of sig figs?Which has the least # of sig figs?

625 has 3, so your answer must have 3625 has 3, so your answer must have 3

4675 x 625 = 2921875 4675 x 625 = 2921875 2920000 = 2.92 x 10 2920000 = 2.92 x 1066

3 sig figs 3 sig figs Rule 4Rule 4

**YOU WILL **YOU WILL USE THIS RULE USE THIS RULE A LOT!!!!!A LOT!!!!!

2.3 Homework

• #32-36 p. 49-51• #40 p. 53• # 42-43, 47 & 51 p. 54• #87, 91, 93-94 p. 63

Documents

Chapter 2 Analyzing Data. Chapter 2 Introduction 2.1 Units & Measurements2.1 Units & Measurements 2.2 Scientific Notation & Dimensional Analysis2.2 Scientific