chapter 1 chemical foundations chy 115: general chemistry i

Chapter 1Chapter 1Chemical FoundationsChemical Foundations

CHY 115: General Chemistry ICHY 115: General Chemistry I

Chapter OutlineChapter Outline Overview of chemistry Overview of chemistry Methods of science – limited coverageMethods of science – limited coverage MeasurementsMeasurements

Unit systemsUnit systems Quantities measuredQuantities measured Taking measurements Taking measurements Accuracy and precision, types of error Accuracy and precision, types of error

Significant figures and calculationsSignificant figures and calculations Dimensional analysisDimensional analysis TemperatureTemperature DensityDensity Classification of matterClassification of matter

ChemistryChemistry

Chemistry – study of the matter of the Chemistry – study of the matter of the universe and the changes that this matter universe and the changes that this matter undergoesundergoes Matter – anything that has mass and occupies Matter – anything that has mass and occupies

spacespace• Examples of matter and “non-matter”Examples of matter and “non-matter”

ChemistryChemistry

What chemists study about the matter:What chemists study about the matter: CompositionComposition StructureStructure PropertiesProperties Chemical changes the matter will undergoChemical changes the matter will undergo Relationship between the matter and:Relationship between the matter and:

• The environmentThe environment• Human health Human health

Better Better living (?) living (?) through through

chemistrychemistry

The Scientific Method The Scientific Method (1.2)(1.2)

The scientific method describes a The scientific method describes a framework by which science is conducted.framework by which science is conducted. Scientific method has been described as Scientific method has been described as

organized common sense.organized common sense. Methodical approach to problem-solving.Methodical approach to problem-solving.

Scientific MethodScientific Method

1.1. Observations Observations questions questions

2.2. Develop hypotheses to explain observationsDevelop hypotheses to explain observations

3.3. Test hypothesesTest hypotheses Make predictions, if hypothesis is true then….Make predictions, if hypothesis is true then…. Test accuracy of the predictionTest accuracy of the prediction Repeat the process, test new hypotheses…Repeat the process, test new hypotheses…

4.4. Analyze results and share findings and Analyze results and share findings and conclusionsconclusions

Scientific InquiryScientific Inquiry

Observations Observations Questions Questions Observations must be recordable and Observations must be recordable and

repeatablerepeatable Observations may be:Observations may be:

• QuantitativeQuantitative

oror

• QualitativeQualitative

TheoriesTheories

After significant research theories/models After significant research theories/models are developed to explain the observationsare developed to explain the observations

Theory – well-tested explanation of some part Theory – well-tested explanation of some part of nature that explains a broad range of of nature that explains a broad range of observationsobservations

• Supported by significant dataSupported by significant data• Subject to rigorous testing and revision when neededSubject to rigorous testing and revision when needed

Natural Law versus TheoryNatural Law versus Theory

Natural LawNatural Law Statement/summary of observed behaviorStatement/summary of observed behavior

• Law of conservation of matterLaw of conservation of matter

Theory Theory (also called a model)(also called a model) Explanation of observed behavior based on Explanation of observed behavior based on

significant datasignificant data Theories attempt to explain lawsTheories attempt to explain laws

Factors Impacting Scientific InquiryFactors Impacting Scientific Inquiry

The direction of scientific research is The direction of scientific research is impacted by many factors:impacted by many factors: Theories and technology of the dayTheories and technology of the day MoneyMoney ReligionReligion PoliticsPolitics World conditionsWorld conditions

Units of Measure Units of Measure (1.3)(1.3)

Much of chemistry is based on analysis of Much of chemistry is based on analysis of quantitative observationsquantitative observations A quantitative observation is obtained by A quantitative observation is obtained by

measurement and includes a number and a measurement and includes a number and a unit.unit.

Unit SystemsUnit Systems

1.1. English systemEnglish system Used in United StatesUsed in United States

2.2. Metric systemMetric system Used in scienceUsed in science

3.3. International system (SI)International system (SI) Based on the metric systemBased on the metric system

UNITS MATTER, see page 9!UNITS MATTER, see page 9!


English SystemEnglish System Used in U.S.Used in U.S. Little logic to the unitsLittle logic to the units

• ExamplesExamples


Metric SystemMetric System Developed in the late 1700’s and adopted Developed in the late 1700’s and adopted

after the French Revolutionafter the French Revolution A base (or fundamental) unit is defined for A base (or fundamental) unit is defined for

each quantity measuredeach quantity measured• The size of the base unit can be modified by The size of the base unit can be modified by

adding a prefixadding a prefix

Unit Systems - metricUnit Systems - metric

Quantity Base unitQuantity Base unit Symbol Symbol

LengthLength MeterMeter mm

MassMass GramGram gg

VolumeVolume LiterLiter L or L or ll

Unit Systems - metericUnit Systems - meteric

Metric Prefixes, Metric Prefixes, see see page 10page 10 MegaMega MM 101066

KiloKilo kk 101033

BASEBASE L, m, gL, m, g 101000

DeciDeci dd 1010-1-1

CentiCenti cc 1010-2-2

MilliMilli mm 1010-3-3

MicroMicro or or mcmc

1010-6-6

NanoNano nn 1010-9-9


Using prefixesUsing prefixes Base unit = meterBase unit = meter Kilometer = km = _________ mKilometer = km = _________ m


International System (SI)International System (SI) Adopted in 1960Adopted in 1960 Internationally agreed upon set of unitsInternationally agreed upon set of units Used in industry and scienceUsed in industry and science

See page 9See page 9

What chemists measureWhat chemists measure

Length – distance between 2 pointsLength – distance between 2 points Metric base = _____________Metric base = _____________

Mass – quantity of matter presentMass – quantity of matter present Base unit: __________Base unit: __________ Weight – measure of gravitational pull on an Weight – measure of gravitational pull on an

objectobject• Base unit: ___________Base unit: ___________

Mass and WeightMass and Weight Measure mass on a balance.Measure mass on a balance.

Measure weight on a scale.Measure weight on a scale.

VolumeVolume

Volume – amount of three dimensional Volume – amount of three dimensional space occupied by an objectspace occupied by an object SI base = meterSI base = meter33

Metric base = Liter = dmMetric base = Liter = dm33

• dm = ______ cmdm = ______ cm

• dmdm33 = ___________ cm = ___________ cm33

Equivalent units: Equivalent units: • mL = _______ = ________mL = _______ = ________

Uncertainty in Measurement Uncertainty in Measurement (1.4)(1.4)

All measurements include some degree of All measurements include some degree of uncertaintyuncertainty A properly taken measurement includes all of A properly taken measurement includes all of

the certain digits and one uncertain the certain digits and one uncertain (estimated) digit(estimated) digit

Taking measurementsTaking measurements

When taking a measurement you record:When taking a measurement you record:• All known digitsAll known digits

those marked on the measuring devicethose marked on the measuring device• One estimated digitOne estimated digit

A multiple of 1/10 the smallest marked unit on A multiple of 1/10 the smallest marked unit on the measuring devicethe measuring device

Taking measurementsTaking measurements

Graduated cylinder exampleGraduated cylinder example

ThermometerThermometer

Example – on boardExample – on board

Accuracy and PrecisionAccuracy and Precision

AccuracyAccuracy – how close a measured value – how close a measured value agrees with the true valueagrees with the true value Ideally values will differ in only the estimated Ideally values will differ in only the estimated

digit digit PrecisionPrecision – how closely repeated – how closely repeated

measurements agree with each othermeasurements agree with each other Ideally the values will differ in only the Ideally the values will differ in only the

estimated digit estimated digit

Types of ErrorsTypes of Errors Random errorRandom error

Value has an equal probability of being high Value has an equal probability of being high or lowor low• Compensate for random errors by averaging Compensate for random errors by averaging

multiple sets of data multiple sets of data

Systematic errorSystematic error Value recorded is consistently low or highValue recorded is consistently low or high

• Compensate for systematic errors by…Compensate for systematic errors by…

Evaluating a measuring deviceEvaluating a measuring device

Good measuring devices are both Good measuring devices are both accurate and preciseaccurate and precise Readings taken with a precise, but not Readings taken with a precise, but not

accurate measuring device can be corrected if accurate measuring device can be corrected if the error is systematic.the error is systematic.

Significant Figures and Significant Figures and Calculations Calculations (1.5)(1.5)

A measurement includes all the certain digits and one estimated (uncertain) digit These digits are called the significant figures

of a measurement.

All calculations based on measurements must reflect the uncertainty of the original measurements.

Significant FiguresSignificant Figures

1.1. Rules for counting significant figuresRules for counting significant figures

2.2. Rules for rounding off calculations based Rules for rounding off calculations based on significant figureson significant figures

Counting Significant FiguresCounting Significant Figures

1.1. All nonzero integers are significant.All nonzero integers are significant. 35.76 g = _______ sig. fig.35.76 g = _______ sig. fig.


2.2. ZerosZeros Leading zeros are NEVER significantLeading zeros are NEVER significant

0.000.0037 mL = _____ sig fig37 mL = _____ sig fig

Captive zeros are ALWAYS significantCaptive zeros are ALWAYS significant 7.7.0098 g = ______ sig. fig.98 g = ______ sig. fig.


2.2. ZerosZeros Trailing zeros are significant Trailing zeros are significant onlyonly if the value if the value

includes a decimal place.includes a decimal place. 35735700 g = ______ sig. fig. g = ______ sig. fig.

7.57.50000 kg = ______ sig. fig. kg = ______ sig. fig.


3.3. Exact Numbers have unlimited significant Exact Numbers have unlimited significant figuresfigures

Numbers obtained by countingNumbers obtained by counting 23 students23 students

DefinitionsDefinitions 1 foot = 12 inches1 foot = 12 inches 1 inch = 2.54 cm (exactly)1 inch = 2.54 cm (exactly)

Rules for Rounding OffRules for Rounding Off

If the first digit to be removed is:If the first digit to be removed is: Less than 5, the preceding digit remains the Less than 5, the preceding digit remains the

samesame

5 or greater, the preceding digit is increased 5 or greater, the preceding digit is increased by 1by 1

Significant Figures and Significant Figures and CalculationsCalculations

Multiplication and DivisionMultiplication and Division The answer is rounded to the same number of The answer is rounded to the same number of

sig. fig. as the measurement with the fewest sig. fig. as the measurement with the fewest sig. fig.sig. fig.

(3.50 x 10(3.50 x 102 2 mL) x 0.7030 g/mL = mL) x 0.7030 g/mL =

oHow to enter #s in scientific notation on your How to enter #s in scientific notation on your calculator calculator

Significant Figures and Significant Figures and CalculationsCalculations

Addition and Subtraction The answer is rounded to the same number of

decimal places as the measurement with the fewest decimal places.

32.05 g + 5.3978 g + 6.30 g =

Dimensional Analysis Dimensional Analysis (1.7)(1.7)

Convert the number of minutes left in class Convert the number of minutes left in class to seconds.to seconds.

Open to back cover of textbook.Open to back cover of textbook.

PRACTICE! PRACTICE!

Dimensional AnalysisDimensional Analysis

The largest pumpkin at the 2012 Windsor The largest pumpkin at the 2012 Windsor fair weighed 1094 pounds.fair weighed 1094 pounds. Express the mass of this pumpkin in grams Express the mass of this pumpkin in grams

and in kg. and in kg.


A block of wood has a volume of 2.50 ftA block of wood has a volume of 2.50 ft33..

Express the volume of the wood block in cmExpress the volume of the wood block in cm33. .


The world's oceans have a surface area of The world's oceans have a surface area of 361,100,000 square kilometers. 361,100,000 square kilometers. Express this surface area in square miles. Express this surface area in square miles.

Please put your final answer in scientific Please put your final answer in scientific notation. notation.


Water has a density of .998 g/mL at room Water has a density of .998 g/mL at room temperature.temperature. Express the density of water in pounds/gallon.Express the density of water in pounds/gallon.

Game plan?Game plan?

Temperature Temperature (1.8)(1.8)

Temperature Scales (units)Temperature Scales (units)1.1. Fahrenheit (Fahrenheit (00F)F)

Used in this countryUsed in this country

2.2. Celsius (Celsius (00C)C) Used in the physical scienceUsed in the physical science

3.3. Kelvin (K)Kelvin (K) SI unit for temperatureSI unit for temperature Used in gas law calculationsUsed in gas law calculations

TemperatureTemperature

FahrenheitFahrenheit CelsiusCelsius KelvinKelvin

Boiling Boiling point waterpoint water

Degrees Degrees between fp and between fp and mpmp

Freezing Freezing point waterpoint water

TemperatureTemperature

FahrenheitFahrenheit00FF

CelsiusCelsius00CC

KelvinKelvin

KK

Boiling Boiling point waterpoint water

212212 100100 373.15373.15

Degrees Degrees between fp and between fp and bpbp

180180 100100 100100

Freezing Freezing point waterpoint water

3232 00 273.15273.15

Temperature ConversionsTemperature Conversions

TTKK = T = TCC + 273.15 + 273.15

TTCC = = (T(TFF - 32) - 32) OR… 5/9 (T OR… 5/9 (TF F - 32)- 32)

1.81.8

TTFF = (1.8) T = (1.8) TCC + 32 …OR… 9/5 x T + 32 …OR… 9/5 x TCC + 32 + 32

Temperature ConversionsTemperature Conversions

Express 68.2Express 68.200 F in in F in in 00C and in KC and in K

Express 78.5Express 78.500 C in C in 00F.F.

Express room temperature in K.Express room temperature in K.

Density Density (1.9)(1.9)

Density = Density = mass of an object mass of an object

volume of objectvolume of object

Density is a physical property that is often Density is a physical property that is often used to identify an object (along with bp used to identify an object (along with bp and mp)and mp)

DensityDensity

Density = Density = mass of an object mass of an object

volume of objectvolume of object

Mass - is expressed in gramsMass - is expressed in grams Volume is expressed in:Volume is expressed in:

• mL or cmmL or cm33 for solids and liquids for solids and liquids• L for gasesL for gases

DensityDensity

Density units:Density units: Solids and LiquidsSolids and Liquids

• g/mL or g/cmg/mL or g/cm3 3

GasesGases• g/Lg/L

English SystemEnglish System• Pounds/footPounds/foot33

DensityDensity

Density of water is ~ 1g/mL at room Density of water is ~ 1g/mL at room temperature.temperature. What is the approximate mass of water in a What is the approximate mass of water in a

0.5 L water bottle?0.5 L water bottle? What is the volume of 150 grams of water?What is the volume of 150 grams of water?

Density - FYIDensity - FYI

Objects with a density greater than 1g/mL Objects with a density greater than 1g/mL sink in water.sink in water.

Objects with a density less than 1g/mL Objects with a density less than 1g/mL float in water.float in water.

Density - FYIDensity - FYI

The density of the elements can be found The density of the elements can be found on the periodic table.on the periodic table. Examples:Examples:

The density of compounds must be looked The density of compounds must be looked up in reference “books”.up in reference “books”.

DensityDensity

Calculating densityCalculating density Convert data to the appropriate unitsConvert data to the appropriate units Plug data into the density formulaPlug data into the density formula Round answer to the correct number of sig. Round answer to the correct number of sig.

fig,fig,

Using Density in Calculations Using Density in Calculations

What is the mass in pounds of a stack of What is the mass in pounds of a stack of boards that measures 4.0 feet by 4.0 feet boards that measures 4.0 feet by 4.0 feet by 8.0 feet if the density of the wood is by 8.0 feet if the density of the wood is 0.74 g/cm0.74 g/cm33. . Game plan?Game plan?

Classification of MatterClassification of Matter(1.10)(1.10)

Physical statesPhysical states Solid, liquid gasSolid, liquid gas

Physical and chemical propertiesPhysical and chemical properties CompositionComposition

• Pure substances - Elements and compoundsPure substances - Elements and compounds• Mixtures - Homogeneous and heterogeneousMixtures - Homogeneous and heterogeneous

Physical States of MatterPhysical States of Matter

A substance’s state of matter is related to A substance’s state of matter is related to the strength of the attractive forces among the strength of the attractive forces among the matter’s particlesthe matter’s particles E.g. solids have very strong attractive forces E.g. solids have very strong attractive forces

between particles and gases very weak forcesbetween particles and gases very weak forces

SolidsSolids

ShapeShape fixed/definitefixed/definite

VolumeVolume fixedfixed Varies slightly with temperatureVaries slightly with temperature

Particles are closely packed, rigidly arranged, Particles are closely packed, rigidly arranged, and strongly attracted to each otherand strongly attracted to each other

LiquidsLiquids

ShapeShape A liquid takes the shape of the bottom of the A liquid takes the shape of the bottom of the

container up to the volume it fillscontainer up to the volume it fills VolumeVolume

fixed/definitefixed/definite Varies slightly with temperatureVaries slightly with temperature

Particles are sliding over each other and Particles are sliding over each other and moderately attracted to each othermoderately attracted to each other

GasesGases

Shape and VolumeShape and Volume A gas takes the shape and volume of a closed A gas takes the shape and volume of a closed

containercontainer• Gases expand or compress to fill a closed Gases expand or compress to fill a closed

containercontainer

Gas particles are far apart, moving very rapidly Gas particles are far apart, moving very rapidly as they bounce off each other and the walls of as they bounce off each other and the walls of the containerthe container Gas particles are very weakly attracted to each otherGas particles are very weakly attracted to each other

Properties of MatterProperties of Matter

Physical propertyPhysical property Characteristic of a substance that can be Characteristic of a substance that can be

determined without changing the chemical determined without changing the chemical composition of the substancecomposition of the substance

Physical changePhysical change Change in a substance’s physical properties Change in a substance’s physical properties

without a change in chemical compositionwithout a change in chemical composition

Properties of MatterProperties of Matter

Chemical propertyChemical property – ability of a substance – ability of a substance to form new substances to form new substances Always involves a change in chemical Always involves a change in chemical

composition of the substancecomposition of the substance Chemical changeChemical change

Change in a substance’s chemical Change in a substance’s chemical compositioncomposition

Also called a chemical reactionAlso called a chemical reaction

Composition of MatterComposition of Matter

Pure SubstancePure Substance - matter with definite - matter with definite compositioncomposition Elements and compoundsElements and compounds are pure are pure

substancessubstances MixtureMixture – matter with variable composition – matter with variable composition

2 or more pure substances present2 or more pure substances present• Not chemically joined/bonded to each otherNot chemically joined/bonded to each other

Pure SubstancesPure Substances

ElementElement – substance that cannot be – substance that cannot be broken down into other substances by broken down into other substances by chemical meanschemical means

CompoundCompound – 2 or more – 2 or more (different)(different) elements joined in a definite ratioelements joined in a definite ratio Compounds can be broken down into Compounds can be broken down into

elements by chemical meanselements by chemical means

MixturesMixtures

MixtureMixture – matter with variable composition – matter with variable composition 2 or more pure substances mixed together2 or more pure substances mixed together The components of a mixture are not joined to The components of a mixture are not joined to

each other in any fixed ratioeach other in any fixed ratio

MixturesMixtures

Homogeneous mixtureHomogeneous mixture Mixture with the same properties throughoutMixture with the same properties throughout

• Also called a solutionAlso called a solution Examples:Examples:

Heterogeneous mixtureHeterogeneous mixture Mixture with regions that have different Mixture with regions that have different

propertiesproperties Examples:Examples:

Separating MixturesSeparating Mixtures

Most matter in the world is a mixtureMost matter in the world is a mixture To separate the components of a mixture, To separate the components of a mixture,

chemists take advantage of differences in chemists take advantage of differences in the physical properties of the mixture’s the physical properties of the mixture’s components.components. Not always easy!Not always easy!


FiltrationFiltration Used to separate a solid from a liquid in a Used to separate a solid from a liquid in a

heterogeneous mixtureheterogeneous mixture


Can filtration be used to separate sugar Can filtration be used to separate sugar from water in sugar water?from water in sugar water? Why or why not?Why or why not?


DistillationDistillation Separates mixtures based upon differences in Separates mixtures based upon differences in

volatilityvolatility• Volatility = Volatility =

• Volatility is related to a substance’s boiling pointVolatility is related to a substance’s boiling point A highly volatile substance will have a _______ boiling A highly volatile substance will have a _______ boiling

points.points.

DistillationDistillation

Distillation works best when there is at Distillation works best when there is at least a 10least a 100 0 C difference in boiling points.C difference in boiling points.

Consider a mixture of water and ethanol.Consider a mixture of water and ethanol. Boiling point water ____________Boiling point water ____________

Boiling point ethanol ______________Boiling point ethanol ______________

Distillation Apparatus


Heat the mixture to the b.p. of the Heat the mixture to the b.p. of the substance with the lower b.p. substance with the lower b.p. Change of state occursChange of state occurs

• Ethanol becomes a gasEthanol becomes a gas• Ethanol vapors expand to fill the distillation Ethanol vapors expand to fill the distillation

apparatusapparatus


Ethanol gas enters the water cooled Ethanol gas enters the water cooled condensing tubecondensing tube Change of state occurs as the ethanol is Change of state occurs as the ethanol is

cooled below __________cooled below __________• Ethanol gas condenses and forms a liquidEthanol gas condenses and forms a liquid• Ethanol liquid drips into the collecting containerEthanol liquid drips into the collecting container


Temperature shoots up to the bp of waterTemperature shoots up to the bp of water Change of state occursChange of state occurs

• Water becomes a gasWater becomes a gas Water vapors expand to fill the distillation Water vapors expand to fill the distillation

apparatusapparatus Water vapors enter the condensing tubeWater vapors enter the condensing tube Water condenses to form a liquid……Water condenses to form a liquid……

chapter 1 chemical foundations chy 115: general chemistry i

Documents

nonmatter slide

matter theory

chemistry slide

space matter

scientific method

qualitativequalitative

repeatable observations

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