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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
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!
Unit SystemsUnit Systems
English SystemEnglish System Used in U.S.Used in U.S. Little logic to the unitsLittle logic to the units
• ExamplesExamples
Unit SystemsUnit Systems
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
Unit SystemsUnit Systems
Using prefixesUsing prefixes Base unit = meterBase unit = meter Kilometer = km = _________ mKilometer = km = _________ m
Unit SystemsUnit Systems
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.
Counting Significant FiguresCounting Significant Figures
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.
Counting Significant FiguresCounting Significant Figures
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.
Counting Significant FiguresCounting Significant Figures
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.
Dimensional AnalysisDimensional Analysis
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. .
Dimensional AnalysisDimensional Analysis
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.
Dimensional AnalysisDimensional Analysis
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!
Separating MixturesSeparating Mixtures
FiltrationFiltration Used to separate a solid from a liquid in a Used to separate a solid from a liquid in a
heterogeneous mixtureheterogeneous mixture
Separating MixturesSeparating Mixtures
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?
Separating MixturesSeparating Mixtures
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 ______________
DistillationDistillation
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
DistillationDistillation
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
DistillationDistillation
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……