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CHEM-111CHEM-111
General ChemistryGeneral Chemistry
Unit-2Unit-2
Matter, Change and EnergyMatter, Change and Energy
by
CHEMISTRY DEPARTMENT

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CONTENTS
1. DEFINITION OF CHEMISTRY
2. THE SCIENTIFIC METHOD
3. TEMPERATURE
4. PHYSICAL STATE OF MATTER
5. MIXTURES
6. PHYSICAL PROPERTIES & PHYSICAL CHANGES
7. CHEMICAL REACTION & CHEMICAL PROPERTIES
8. ELEMENTS & COMPOUNDS
9. MASS CONVERSION
10. ENERGY INTERCONVERSION
11. EXOTHERMIC AND ENDOTHERMIC PROCESS
Matter, Change, and EnergyMatter, Change, and Energy

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Chemistry is the study of, mainly theChemistry is the study of, mainly the
composition, structure, reactions andcomposition, structure, reactions and
properties of matterproperties of matter . Some main branches are-. Some main branches are-
BiochemistryBiochemistry Study of biological chemicalsStudy of biological chemicals
Organic chemistryOrganic chemistry Carbon based compoundsCarbon based compounds
Inorganic chemistryInorganic chemistry All other elementsAll other elements
Analytical chemistryAnalytical chemistry Methods of analysisMethods of analysis
Physical chemistryPhysical chemistry Theory and conceptsTheory and concepts
Branches of ChemistryBranches of Chemistry

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MATTERMATTER
Anything thatAnything that occupies spaceoccupies space andand has masshas mass isis
calledcalled mattermatter..
Specific kind of matter is calledSpecific kind of matter is called material.material.
MassMass is the measurement of amount of matteris the measurement of amount of matter
present in an object.present in an object.
All the chemicals that make up our world areAll the chemicals that make up our world are
example of matter,example of matter,
whether they may be found in medicines,whether they may be found in medicines,
pencils, food or people.pencils, food or people.

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Materials
Specific kind of matter
Steel, ocean water, glass, sand, blood
Homogeneous
Uniform distribution of
particles
Heterogeneous
Non uniform distribution of
particles
Homogeneous mixtures
Two materials present in uniform
Composition throughout
Heterogeneous mixture
Two materials present in non uniform
Composition throughout
Substances
Homogenous material with the
Same composition, pure,
Non mixtures
Elements
Composed of one kind of
atoms
Compounds
Composed of more than one
Kind of atoms
Solutions
Uniform distribution of two
materials

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What are elements?What are elements?
All matter are made up of elements ,whichAll matter are made up of elements ,which are primaryare primary
substances, cannot be broken down by chemical meanssubstances, cannot be broken down by chemical means..
There are now 115 different kinds of elements. Of these,There are now 115 different kinds of elements. Of these,
92 elements occur naturally and are found in different92 elements occur naturally and are found in different
combinations.combinations.
Hydrogen (H), carbon (C), nitrogen (N) and oxygen (O) areHydrogen (H), carbon (C), nitrogen (N) and oxygen (O) are
the elements that make upthe elements that make up most living organismsmost living organisms..
Some other elements found in living organisms are:Some other elements found in living organisms are:
Magnesium (Mg), calcium (Ca), phosphorus (P), sodium (Na),Magnesium (Mg), calcium (Ca), phosphorus (P), sodium (Na),
potassium (k)potassium (k)..

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Elements and CompoundsElements and Compounds
Iron (Fe) andIron (Fe) and
CompoundsCompounds
Mercury (Hg) andMercury (Hg) and
compoundscompounds
Two or more elementsTwo or more elements chemically combinedchemically combined to form newto form new
substance called asubstance called a compoundcompound..
Proteins, carbohydrates, lipids, water, salt, carbonProteins, carbohydrates, lipids, water, salt, carbon
dioxide and hemoglobin are few examples of compounds.dioxide and hemoglobin are few examples of compounds.

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disorderdisordershort rangeshort range
orderorder
SolidSolid
States of MatterStates of Matter
GasGasLiquidLiquid
long rangelong range
orderorder
havehave vibration motionvibration motion.. are inare in constant random motionconstant random motion.. free to move randomlyfree to move randomly
MoleculesMolecules MoleculesMolecules MoleculesMolecules

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StatesStates
ofof
MatterMatter
FluidityFluidity
oror
RigidityRigidity
CompresCompres
-sibility-sibility
VolumeVolume ShapeShape
Inter-Inter-
molecularmolecular
spacespace
Inter-Inter-
molecularmolecular
forcesforces
SolidsSolids RigidRigid NoNo FixedFixed FixedFixed Very LessVery Less StrongStrong
LiquidsLiquids
FluidFluid Very LowVery Low FixedFixed
NotNot
FixedFixed
SlightlySlightly
moremore
LessLess
strong orstrong or
WeakWeak
GasesGases FluidFluid Very HighVery High
NotNot
FixedFixed
NotNot
FixedFixed
MoreMore
ExtremelyExtremely
WeakWeak
Characteristics of MatterCharacteristics of Matter

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Change of State of MatterChange of State of Matter
HH22OO
IceIce VaporVaporWaterWater
Water changes from solid to liquid & then gas byWater changes from solid to liquid & then gas by
heating.heating.
It is aIt is a physical changephysical change which changes thewhich changes the
arrangement of water moleculesarrangement of water molecules only,only, not thenot the
formula of water.formula of water.
solidsolid gasgasliquidliquid

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MixturesMixtures
TheThe mixingmixing oror combinationcombination of two or moreof two or more
substances is known assubstances is known as a mixturea mixture..
There isThere is no chemical bonding existsno chemical bonding exists amongamong
the substances present in mixturesthe substances present in mixtures..
AirAir is a mixture of many gasesis a mixture of many gases..
Plasma, urine and bloodPlasma, urine and blood are also few examplesare also few examples
of mixturesof mixtures..

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Mixture of gases constituting the earth's atmosphere. Some gases occur in steady concentrations.Mixture of gases constituting the earth's atmosphere. Some gases occur in steady concentrations.
The most important are molecular nitrogen (NThe most important are molecular nitrogen (N2), 78%2), 78% by volume, and molecular oxygen (Oby volume, and molecular oxygen (O2),2),
21%.21%. Small amounts of argon (Ar; 1.9%), neon (Ne), helium (He), methane (CHSmall amounts of argon (Ar; 1.9%), neon (Ne), helium (He), methane (CH4),4), krypton (Kr),krypton (Kr),
hydrogen (Hhydrogen (H2),2), nitrous oxide (Nnitrous oxide (N22O), and xenon (Xe) are also present in almost constantO), and xenon (Xe) are also present in almost constant
proportions. Other gases occur in variable concentrations: water vapour (Hproportions. Other gases occur in variable concentrations: water vapour (H22O), ozone (OO), ozone (O3),3),
carbon dioxide (CO2carbon dioxide (CO22),2), sulfur dioxide (SO2sulfur dioxide (SO22),2), and nitrogen dioxide (NO2and nitrogen dioxide (NO222(.(.

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Two categories of mixtures are:Two categories of mixtures are:
1- HOMOGENEOUS1- HOMOGENEOUS (Uniform composition)(Uniform composition)
ExampleExample ––Plasma, sugar solution etc.Plasma, sugar solution etc.
2-HETEROGENEOUS2-HETEROGENEOUS ((Non-uniform composition)Non-uniform composition)
ExampleExample ––Blood, Urine, Oil with water etc.Blood, Urine, Oil with water etc.
Mixtures:
Oil and waterOil and water
forms aforms a
heterogeneousheterogeneous
mixturesmixtures
before shakingbefore shaking after shakingafter shaking
Oil
water

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Difference betweenDifference between Compound and MixtureCompound and Mixture
1- The temperature of1- The temperature of compoundcompound will stay constantwill stay constant
as it melts butas it melts but temperature, intemperature, in mixturemixture of aof a
substance will change gradually.substance will change gradually.
Example:Example: Ice melts at 0Ice melts at 0 00
C. While mixture of iceC. While mixture of ice
with NaCl melts, at lower temperature than 0with NaCl melts, at lower temperature than 0 00
C.C.
2- The2- The identity & chemical propertiesidentity & chemical properties of substancesof substances
are changed in preparation of compound. Whileare changed in preparation of compound. While
component of a mixture retain their chemicalcomponent of a mixture retain their chemical
properties.properties.
Example:Example:
A mixture of Cu and S can be observed before andA mixture of Cu and S can be observed before and
after chemical change.after chemical change.

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Formation of compound is a chemical changeFormation of compound is a chemical change,,
Mixture is formed by physical changeMixture is formed by physical change
coil of red –coil of red –
colored coppercolored copper
wire andwire and
yellow powderedyellow powdered
sulfur.sulfur.
When mixed inWhen mixed in
the crucible, thethe crucible, the
copper and sulfurcopper and sulfur
retain theirretain their
individualindividual
propertiesproperties
When the mixture ofWhen the mixture of
copper and sulfur iscopper and sulfur is
heated a reaction takesheated a reaction takes
place and a newplace and a new
substance calledsubstance called
copper sulfide iscopper sulfide is
formed.,formed.,
CuSCuS
compoundcompound

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Physical PropertyPhysical Property
Property which is observed without changing theProperty which is observed without changing the
chemical makeup of a substance.chemical makeup of a substance.
For example melting point of ice is 0For example melting point of ice is 000
C and boiling pointC and boiling point
of water is 100of water is 10000
C which is always found same in normalC which is always found same in normal
conditions.conditions.
Formula of water , water vapors and ice remainsFormula of water , water vapors and ice remains
same,Hsame,H22O, in all these physical sates..O, in all these physical sates..
Qualitative PropertyQualitative Property Quantitative PropertyQuantitative Property
colorcolor densitydensity
odorodor melting pointmelting point
tastetaste boiling pointboiling point
feel or touchfeel or touch compressibilitycompressibility

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The change that does not change the chemicalThe change that does not change the chemical
structure of a substance.structure of a substance. e.g.e.g.
Examples:Examples:
1.1. Change of ice to liquid,Change of ice to liquid, does not affect chemicaldoes not affect chemical
formula of Hformula of H22O .O .
2.2. A beaker and brokenA beaker and broken beakerbeaker-composition remains-composition remains
same, so physical change.same, so physical change.
3.3. Melting of wax on heating and again solidificationMelting of wax on heating and again solidification
onon coolingcooling ..
4.4. Sublimation of iodine is also a physical changeSublimation of iodine is also a physical change
Sublimation of iodineSublimation of iodine
Physical ChangePhysical Change

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Chemical Reactions
The study of changes that occur when chemicals interact with
each other to form entirely different substances.

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The symbolic representation of a chemicalThe symbolic representation of a chemical
substance in form of assembled symbolssubstance in form of assembled symbols
MOLECULAR REPRESENTATIONSMOLECULAR REPRESENTATIONS
HH22O-waterO-water
Formula are used
to represent :
1. How many are
there of each
element
2. How the
elements are
connected to
each other.
3. The names of
elements in a
compound.
CHCH33CHCH22OH-ethyl alcoholOH-ethyl alcohol
2 hydrogen2 hydrogen
1 oxygen1 oxygen
2 carbon,2 carbon,
6 Hydrogen6 Hydrogen
1 oxygen1 oxygen
Chemical FormulaChemical Formula
ExamplesExamples

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Chemical ChangeChemical Change
In, a chemical change the reacting substances change into newIn, a chemical change the reacting substances change into new
substances that have different formulas and different properties.substances that have different formulas and different properties.
For instance , when silver tarnishes, the bright silver metalFor instance , when silver tarnishes, the bright silver metal
becomes dull because it changes into Agbecomes dull because it changes into Ag22S.S.
Tarnishing of silverTarnishing of silver
2 Ag + S Ag2 Ag + S Ag22SS
silver sulphidesilver sulphide
Rusting of ironRusting of iron
4 Fe + 3 O4 Fe + 3 O22 2Fe2Fe22 OO33
ironiron oxygenoxygen iron oxideiron oxide

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Evidences of Chemical ChangeEvidences of Chemical Change
•New substances produced, old substances destroyedNew substances produced, old substances destroyed
•Heat added or absorbedHeat added or absorbed
•Water formedWater formed
•Color changeColor change
•Odor changeOdor change
•Gas ProducedGas Produced•Light added or absorbedLight added or absorbed
•Precipitation (solid formed)Precipitation (solid formed)
•Explosion (fast gas)Explosion (fast gas)
LightLight GasGas ExplosionExplosion

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Comparison of Some Chemical andComparison of Some Chemical and
Physical ChangesPhysical Changes
Chemical ChangesChemical Changes Physical ChangesPhysical Changes
Rusting nailRusting nail Melting iceMelting ice
Bleaching a stainBleaching a stain Boiling waterBoiling water
Burning woodBurning wood cutting woodcutting wood
Tarnishing silverTarnishing silver Tearing paperTearing paper
Fermenting grapesFermenting grapes Breaking a glassBreaking a glass
Souring of milkSouring of milk Pouring milkPouring milk

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Energy and HeatEnergy and Heat
Energy:Energy: is defined as the ability to do workis defined as the ability to do work..
Classification of EnergyClassification of Energy
1-Potential energy (stored energy)1-Potential energy (stored energy)
2-Kinetic energy (energy of motion)2-Kinetic energy (energy of motion)
The food you eat has potential energy.The food you eat has potential energy.
When you digest, you convert its potential energyWhen you digest, you convert its potential energy
to kinetic energy to do work in the body.to kinetic energy to do work in the body.

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Kinetic Theory of MatterKinetic Theory of Matter
Matter is composed of small
particles; atoms, molecules.
They are in constant & random
motion.
Particles due to continuousParticles due to continuous
motion possess kinetic energy.motion possess kinetic energy.
K.E=1/2mvK.E=1/2mv22
K.E (K.E (avav) T () T (absabs).).∝
molecules
Magnified view of

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Energy in Chemical Reactions
Reactions
Lost Gained
Exothermic Endothermic
Reversible
Chemical
equilibrium
with heat that is
are are
and reach
that occur in both directions are

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Heat Capacity of Matter
HeatHeat is the energy associated with the motion ofis the energy associated with the motion of
particles in a substanceparticles in a substance
 An energy change often shows that a chemical
reaction is happening.
 Sometimes heat energy isSometimes heat energy is given outgiven out and theand the
chemicals getchemicals get hothot..
These reactions areThese reactions are calledcalled ExothermicExothermic
reactions.reactions.
 In other reaction, heat energy isIn other reaction, heat energy is taken intaken in andand
the chemicals getthe chemicals get coldercolder..
These are calledThese are called Endothermic reactions.Endothermic reactions.

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Exothermic and Endothermic ReactionsExothermic and Endothermic Reactions
 Heat of Reaction:Heat of Reaction:
Energy difference between reactants and theEnergy difference between reactants and the
productsproducts
 Exothermic reaction:Exothermic reaction:
Energy of the product isEnergy of the product is lowerlower than thethan the
reactant and heat isreactant and heat is given outgiven out..
 Endothermic reaction:Endothermic reaction:
EnergyEnergy of the product isof the product is higherhigher than thethan the
reactant and heat must bereactant and heat must be absorbedabsorbed forfor
products to form.products to form.

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Exothermic and Endothermic ReactionsExothermic and Endothermic Reactions
ExamplesExamples
 Exothermic ReactionExothermic Reaction
CHCH44 + 2O+ 2O22 COCO22 + 2H+ 2H22O + 213kcalO + 213kcal
Endothermic ReactionEndothermic Reaction
HH22 + I+ I22 + 12 kcal of heat 2HI+ 12 kcal of heat 2HI
ReactionReaction Energy ChangeEnergy Change Heat in the EquationHeat in the Equation
Exothermic Heat releasedExothermic Heat released Product sideProduct side
Endothermic Heat absorbedEndothermic Heat absorbed Reactant sideReactant side
Heat absorbedHeat absorbed
MethaneMethane Heat releasedHeat released

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1.1. Which are homogeneous or heterogeneous mixtures?Which are homogeneous or heterogeneous mixtures?
Chips, Urine, Gasoline,Chips, Urine, Gasoline, Salad dressingSalad dressing
Homogenized milk , sugar solution, butter, Raisins,Homogenized milk , sugar solution, butter, Raisins,
nuts.nuts.
2.2. Identify each of the following as a solid, a liquid, or a gas.Identify each of the following as a solid, a liquid, or a gas.
Water, iron , oil, helium, salt, vinegar, air, Ice, water vapor.Water, iron , oil, helium, salt, vinegar, air, Ice, water vapor.
3.3. Classify each of the following changes as chemical orClassify each of the following changes as chemical or
physicalphysical..
a. drying clotha. drying cloth b. digesting a chocolate barb. digesting a chocolate bar
c. breaking a chocolate barc. breaking a chocolate bar d. burning paperd. burning paper
4.4. Solve the following temperature conversions.Solve the following temperature conversions.
a. 37.0a. 37.0 00
C = ----------C = ----------00
FF b. 65.3b. 65.3 00
F = ---------F = ---------00
CC
c. 545K = ---------c. 545K = ---------00
CC d. 224K = ----------d. 224K = ----------00
CC
ExerciseExercise

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6.6. Identify elements, compounds and mixtures.Identify elements, compounds and mixtures.
a. aira. air b. waterb. water c. Pepsic. Pepsi d. carbond. carbon
e. milke. milk f. bloodf. blood g. goldg. gold h. table salth. table salt
7.7. Identify each of following changes of the state as evaporation,Identify each of following changes of the state as evaporation,
boiling, or condensation.boiling, or condensation.
a. a shallow pond dries up in the summera. a shallow pond dries up in the summer
b. the water vapors in the cloud changes to rain.b. the water vapors in the cloud changes to rain.
c. your tea kettle whistles when water is ready for tea.c. your tea kettle whistles when water is ready for tea.
8.8. Classify the following as exothermic or endothermic reaction.Classify the following as exothermic or endothermic reaction.
a. combustion of propane:a. combustion of propane:
CC33HH88 + 5O+ 5O22 3CO3CO22 + 4H+ 4H22O + 531 kcalO + 531 kcal
b. the formation of “table” salt:b. the formation of “table” salt:
2Na + Cl2Na + Cl22 2NaCl + 196 kcal2NaCl + 196 kcal
c.c. decomposition of phosphorous pentachloride:decomposition of phosphorous pentachloride:
PClPCl55 + 16 kcal+ 16 kcal PClPCl33 + Cl+ Cl22