chapter 1: chemical foundations the scientific method units of measurement uncertainty in...

Chapter 1:Chemical Foundations

The Scientific Method

Units of Measurement

Uncertainty in Measurement

Significant Figures

Dimensional Analysis

Temperature

Density

Classification of Matter

Why Study ChemistryWhy Study Chemistry

• Every aspect of our lives are based on chemistry.Every aspect of our lives are based on chemistry.

• Microscopically (vs. macroscopically), Microscopically (vs. macroscopically), everything is composed of atoms.everything is composed of atoms.

• Is a tool to help understand and the world Is a tool to help understand and the world around you.around you.

Scientific MethodScientific Method

A systematic approach to solving problems.A systematic approach to solving problems.

General DefinitionsGeneral Definitions• ChemistryChemistry – study of the properties of materials and the changes that the – study of the properties of materials and the changes that the

material undergoes.material undergoes.

• MatterMatter – The physical material of the universe; anything that has mass and – The physical material of the universe; anything that has mass and takes up space.takes up space.

• ElementsElements – A substance that cannot be separated into simpler substances by – A substance that cannot be separated into simpler substances by chemical means.chemical means.

• AtomsAtoms – Building blocks o– Building blocks of matter, the smallest representative particle of an f matter, the smallest representative particle of an element.element.

• MoleculesMolecules – Atoms that are held together in specific shapes.– Atoms that are held together in specific shapes.

ChemistryChemistry

The study of The study of mattermatter and the and the changeschanges it it undergoes.undergoes.

ChemistryChemistry

SolidSolid – both a definite – both a definite shape and definite volumeshape and definite volume

LiquidLiquid – distinct volume – distinct volume independent of it’s independent of it’s container, so specific container, so specific shapeshape

GasGas – no fixed volume or – no fixed volume or shapeshape

ChemistryChemistrySolidSolid – molecules held – molecules held together tightly; only together tightly; only “wiggling” slightly“wiggling” slightly

LiquidLiquid – molecules are – molecules are packed more closely packed more closely together than gas, less together than gas, less tightly than solid; allows for tightly than solid; allows for molecules to slide over each molecules to slide over each other other

GasGas – Molecules are far – Molecules are far apart, colliding only briefly apart, colliding only briefly with each other and with the with each other and with the wall of the containerwall of the container

States of MatterStates of Matter

MatterMatter

Anything that has mass and Anything that has mass and takes up space.takes up space.

MatterMatter

• AtomsAtoms are the building blocks of matter.are the building blocks of matter.• Each Each elementelement is made of the same kind of atom.is made of the same kind of atom.

MatterMatter

• AtomsAtoms are the building blocks of matter.are the building blocks of matter.• EachEach elementelement is made of the same kind of atom.is made of the same kind of atom.• AA compoundcompound is made of two or more different is made of two or more different

kinds of elements.kinds of elements.

Classification of MatterClassification of Matter

Uncertainty in Uncertainty in MeasurementMeasurement

Significant FiguresSignificant Figures

• The term The term significant figuressignificant figures refers to refers to digits that were measured.digits that were measured.

• When rounding calculated numbers, When rounding calculated numbers, we pay attention to significant figures we pay attention to significant figures so we do not over/understate the so we do not over/understate the accuracy of our answers.accuracy of our answers.


1.1. All nonzero digits are significant.All nonzero digits are significant.2.2. Zeroes between two significant Zeroes between two significant

figures are themselves significant.figures are themselves significant.3.3. Zeroes at the beginning of a number Zeroes at the beginning of a number

are never significant.are never significant.4.4. Zeroes at the end of a number are Zeroes at the end of a number are

significant if a decimal point is significant if a decimal point is written in the number.written in the number.


Examples: Examples: #Sig Fig#Sig Fig Rule(s) Rule(s)

AppliedApplied0.0210.021106410640.30070.300714.23214.2324300.004300.000.050820.05082


• When addition or subtraction is performed, When addition or subtraction is performed, answers are rounded to the least significant answers are rounded to the least significant decimal placedecimal place..

• When multiplication or division is When multiplication or division is performed, answers are rounded to the performed, answers are rounded to the number of digits that corresponds to the number of digits that corresponds to the leastleast number of significant figuresnumber of significant figures in any of in any of the numbers used in the calculation.the numbers used in the calculation.

Accuracy versus PrecisionAccuracy versus Precision

• AccuracyAccuracy refers to the proximity refers to the proximity of a measurement to the true of a measurement to the true value of a quantity.value of a quantity.

• PrecisionPrecision refers to the proximity refers to the proximity of several measurements to each of several measurements to each other.other.

Dimensional AnalysisDimensional Analysis

Metric SystemMetric SystemUnit = labelUnit = label

““What do you have?” “I have 3.”What do you have?” “I have 3.”““How much coffee do you want?” “I want four.”How much coffee do you want?” “I want four.”

Metric based off Metric based off

UnitUnit USUS Metric MetricWeight/MassWeight/MassLengthLengthVolumeVolume


• Conversion Factor - “ratio that converts a Conversion Factor - “ratio that converts a measure expressed in one unit to a measure expressed in one unit to a measure expressed in another unit”.measure expressed in another unit”.

• Always equal to “1”Always equal to “1”


ExampleExampleA vitamin C tablet is found to contain 0.500 g of A vitamin C tablet is found to contain 0.500 g of vitamin C. How many milligrams of vitamin C vitamin C. How many milligrams of vitamin C does this table contain?does this table contain?

GivenGiven KnownKnown QuestionQuestion


ExampleExampleA piece of copper metal has a mass of 17.6 lb. A piece of copper metal has a mass of 17.6 lb.

What is the copper mass in kilograms?What is the copper mass in kilograms?



ExampleExampleThe estimated amount of recoverable oil from the field The estimated amount of recoverable oil from the field at Prudhoe Bay in Alaska is 4.0 x 10at Prudhoe Bay in Alaska is 4.0 x 101111 gal. What is the gal. What is the amount in fluid ounces (fl. Oz)?amount in fluid ounces (fl. Oz)?


Units of Units of MeasurementMeasurement

SI UnitsSI Units

• Système International d’UnitésSystème International d’Unités

• Uses a different base unit for each quantityUses a different base unit for each quantity

Metric SystemMetric System

Prefixes convert the base units into units that Prefixes convert the base units into units that are appropriate for the item being measured.are appropriate for the item being measured.

VolumeVolume

• The most commonly The most commonly used metric units for used metric units for volume are the liter (L) volume are the liter (L) and the milliliter (mL).and the milliliter (mL).□ A liter is a cube 1 dm A liter is a cube 1 dm

long on each side.long on each side.

□ A milliliter is a cube 1 A milliliter is a cube 1 cm long on each side.cm long on each side.

Uncertainty in MeasurementsUncertainty in Measurements

Different measuring devices have different Different measuring devices have different uses and different degrees of accuracy.uses and different degrees of accuracy.

TemperatureTemperature

A measure of the A measure of the average kinetic average kinetic energy of the energy of the particles in a particles in a sample.sample.


• In scientific In scientific measurements, the measurements, the Celsius and Kelvin Celsius and Kelvin scales are most often scales are most often used.used.

• The Celsius scale is The Celsius scale is based on the properties based on the properties of water.of water.□ 00C is the freezing point C is the freezing point

of water.of water.

□ 100100C is the boiling C is the boiling point of water.point of water.


• The Kelvin is the SI The Kelvin is the SI unit of temperature.unit of temperature.

• It is based on the It is based on the properties of gases.properties of gases.

• There are no There are no negative Kelvin negative Kelvin temperatures.temperatures.

• K = K = C + 273.15C + 273.15


• The Fahrenheit The Fahrenheit scale is not used in scale is not used in scientific scientific measurements.measurements.

F = 9/5(F = 9/5(C) + 32C) + 32 C = 5/9(C = 5/9(F F −− 32) 32)

DensityDensity

Physical property of a substancePhysical property of a substance

d d = = mmVV

Properties and Properties and Changes of Changes of

MatterMatter

Properties of MatterProperties of Matter

• Physical Properties:Physical Properties:□ Can be observed without changing a substance Can be observed without changing a substance

into another substance.into another substance.• Boiling point, density, mass, volume, etc.Boiling point, density, mass, volume, etc.

• Chemical Properties:Chemical Properties:□ Can Can onlyonly be observed when a substance is be observed when a substance is

changed into another substance.changed into another substance.• Flammability, corrosiveness, reactivity with acid, etc.Flammability, corrosiveness, reactivity with acid, etc.

Properties of MatterProperties of Matter

• Intensive Properties:Intensive Properties:□ Independent of the amount of the Independent of the amount of the

substance that is present.substance that is present.• Density, boiling point, color, etc.Density, boiling point, color, etc.

• Extensive Properties:Extensive Properties:□ Dependent upon the amount of the Dependent upon the amount of the

substance present.substance present.• Mass, volume, energy, etc.Mass, volume, energy, etc.

Changes of MatterChanges of Matter

• Physical Changes:Physical Changes:□ Changes in matter that do not change the Changes in matter that do not change the

composition of a substance.composition of a substance.• Changes of state, temperature, volume, etc.Changes of state, temperature, volume, etc.

• Chemical Changes:Chemical Changes:□ Changes that result in new substances.Changes that result in new substances.

• Combustion, oxidation, decomposition, etc.Combustion, oxidation, decomposition, etc.

Chemical ReactionsChemical Reactions

In the course of a chemical reaction, the In the course of a chemical reaction, the reacting substances are converted to new reacting substances are converted to new substances.substances.

CompoundsCompounds

Compounds can be Compounds can be broken down into broken down into more elemental more elemental particles.particles.

Electrolysis of WaterElectrolysis of Water

Separation of Separation of MixturesMixtures

DistillationDistillation

Separates Separates homogeneous homogeneous mixture on the mixture on the basis of differences basis of differences in boiling point.in boiling point.

DistillationDistillation

FiltrationFiltration

Separates solid Separates solid substances from substances from liquids and solutions.liquids and solutions.

ChromatographyChromatographySeparates substances on the basis of Separates substances on the basis of differences in solubility in a solvent.differences in solubility in a solvent.

Chapter 1:Chemical Foundations

The Scientific Method

Units of Measurement

Uncertainty in Measurement

Significant Figures

Dimensional Analysis

Temperature

Density

Classification of Matter

chapter 1: chemical foundations the scientific method units of measurement uncertainty in...

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measurement slide

shape slide

states of matter slide

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matter atoms

study of matter

building blocks of matter

molecules atoms