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CHEM-111CHEM-111General ChemistryGeneral Chemistry

Unit-2Unit-2Matter, Change and EnergyMatter, Change and Energy

byCHEMISTRY DEPARTMENT

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CONTENTS1. DEFINITION OF CHEMISTRY2. THE SCIENTIFIC METHOD3. TEMPERATURE4. PHYSICAL STATE OF MATTER5. MIXTURES6. PHYSICAL PROPERTIES & PHYSICAL CHANGES7. CHEMICAL REACTION & CHEMICAL PROPERTIES8. ELEMENTS & COMPOUNDS9. MASS CONVERSION10. ENERGY INTERCONVERSION11. EXOTHERMIC AND ENDOTHERMIC PROCESS

Matter, Change, and EnergyMatter, Change, and Energy

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Chemistry is the study of, mainly the Chemistry is the study of, mainly the composition, structure, reactions and composition, structure, reactions and properties of matterproperties of matter . Some main branches are- . Some main branches are-Biochemistry Biochemistry Study of biological chemicalsStudy of biological chemicalsOrganic chemistryOrganic chemistry Carbon based compoundsCarbon based compoundsInorganic chemistryInorganic chemistry All other elementsAll other elementsAnalytical chemistryAnalytical chemistry Methods of analysisMethods of analysisPhysical chemistryPhysical chemistry Theory and conceptsTheory and concepts

Branches of ChemistryBranches of Chemistry

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MATTERMATTER

Anything that Anything that occupies spaceoccupies space and and has has massmass is called is called mattermatter..

Specific kind of matter is called Specific kind of matter is called material.material.

MassMass is the measurement of amount is the measurement of amount of matter present in an object.of matter present in an object.

All the chemicals that make up our All the chemicals that make up our

world are example of matter, world are example of matter, whether they may be found in whether they may be found in

medicines, pencils, food or people.medicines, pencils, food or people.

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Materials Specific kind of matterSteel, ocean water, glass, sand, blood

HomogeneousUniform distribution of particles

HeterogeneousNon uniform distribution of particles

Homogeneous mixturesTwo materials present in uniform Composition throughout

Heterogeneous mixtureTwo materials present in non uniform Composition throughout

SubstancesHomogenous material with the Same composition, pure, Non mixtures

ElementsComposed of one kind of atoms

CompoundsComposed of more than oneKind of atoms

SolutionsUniform distribution of twomaterials

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What are elements? What are elements?

All matter are made up of elements ,which All 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 different 92 elements occur naturally and are found in different combinations.combinations.

Hydrogen (H), carbon (C), nitrogen (N) and oxygen (O) are Hydrogen (H), carbon (C), nitrogen (N) and oxygen (O) are the elements that make up the 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) andCompoundsCompounds

Mercury (Hg) andMercury (Hg) andcompoundscompounds

Two or more elements Two or more elements chemically combinedchemically combined to form new to form new substance called a substance called a compoundcompound..

Proteins, carbohydrates, lipids, water, salt, carbon Proteins, 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 range short range orderorder

SolidSolid

States of MatterStates of Matter

GasGasLiquidLiquid

long range long range orderorder

have have vibration motionvibration motion.. are in are in constant random motionconstant random motion.. free to move randomlyfree to move randomly

MoleculesMolecules MoleculesMolecules MoleculesMolecules

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States States of of

MatterMatter

FluiditFluidity or y or

RigiditRigidityy

CompreCompres-s-

sibilitysibility

VolumVolumee

ShapShapee

Inter-Inter-moleculamolecular spacer space

Inter-Inter-moleculamolecular forcesr forces

SolidsSolidsRigidRigidNoNoFixedFixedFixedFixedVery LessVery LessStrongStrong

LiquidsLiquidsFluidFluidVery LowVery LowFixedFixed

NotNot

FixedFixedSlightly Slightly

moremore

Less Less strong or strong or

WeakWeak

GasesGasesFluidFluidVery Very HighHigh

Not Not FixedFixed

Not Not FixedFixedMoreMoreExtremely Extremely

WeakWeak

Characteristics of MatterCharacteristics of Matter

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Change of State of MatterChange of State of Matter

HH22OO

IceIce VaporVapor WaterWater

Water changes from solid to liquid & then gas by Water changes from solid to liquid & then gas by heating. heating.

It is a It is a physical changephysical change which changes the which changes the arrangement of water moleculesarrangement of water molecules only, only, not the not the

formula of water.formula of water.

solidsolid gasgasliquidliquid

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MixturesMixtures

The The mixingmixing or or combinationcombination of two or more of two or more substances is known as substances is known as a mixturea mixture..

There is There is no chemical bonding existsno chemical bonding exists among the substances present in among the substances present in

mixturesmixtures..

AirAir is a mixture of many gases is a mixture of many gases . .Plasma, urine and bloodPlasma, urine and blood are also few are also few

examples of mixturesexamples of mixtures..

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Mixture of gases constituting the earth's atmosphere. Some gases occur Mixture of gases constituting the earth's atmosphere. Some gases occur in steady concentrations. The most important are molecular nitrogen in steady concentrations. The most important are molecular nitrogen (N(N2), 78% 2), 78% by volume, and molecular oxygen (Oby volume, and molecular oxygen (O2), 21%. 2), 21%. Small amounts of Small amounts of argon (Ar; 1.9%), neon (Ne), helium (He), methane (CHargon (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 O), and xenon (Xe) are also present in almost constant proportions. Other gases occur in variable almost constant proportions. Other gases occur in variable concentrations: water vapour (Hconcentrations: 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 (NO22)2)..

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Two categories of mixtures are:Two categories of mixtures are:1- HOMOGENEOUS1- HOMOGENEOUS (Uniform composition)(Uniform composition) Example Example ––Plasma, sugar solution etc.Plasma, sugar solution etc.

2-HETEROGENEOUS 2-HETEROGENEOUS ((Non-uniform composition)Non-uniform composition) ExampleExample – –Blood, Urine, Oil with water etc.Blood, Urine, Oil with water etc.

Mixtures:

Oil and water Oil and water forms a forms a

heterogeneous heterogeneous mixturesmixtures

before shakingbefore shaking after shakingafter shaking

Oil

water

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Difference betweenDifference between Compound and MixtureCompound and Mixture1- The temperature of 1- The temperature of compoundcompound will stay constant will stay constant as it melts butas it melts but temperature, in temperature, in mixturemixture of a of a substance will change gradually. substance will change gradually. Example: Example: Ice melts at 0 Ice melts at 0 00C. While mixture of ice C. While mixture of ice with NaCl melts, at lower temperature than 0 with NaCl melts, at lower temperature than 0 00C.C.

2- The 2- The identity & chemical propertiesidentity & chemical properties of substances of substances are changed in preparation of compound. While are changed in preparation of compound. While component of a mixture retain their chemical component of a mixture retain their chemical properties.properties. Example:Example: A mixture of Cu and S can be observed before and A 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 copper colored copper

wire andwire andyellow powdered yellow powdered

sulfur.sulfur.

When mixed in When mixed in the crucible, the the crucible, the

copper and sulfur copper and sulfur retain their retain their individual individual propertiesproperties

When the mixture of When the mixture of copper and sulfur is copper and sulfur is

heated a reaction takes heated a reaction takes place and a new place and a new substance called substance called copper sulfide is copper sulfide is

formed., formed.,

CuSCuS

compoundcompound

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Physical PropertyPhysical PropertyProperty which is observed without changing the Property 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 000C and boiling point C and boiling point of water is 100of water is 10000C which is always found same in normal C which is always found same in normal conditions.conditions.Formula of water , water vapors and ice remains Formula 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 Propertycolorcolor density density

odorodor melting point melting point tastetaste boiling point boiling point feel or touchfeel or touch compressibility compressibility

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The change that does not change the chemical The 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 chemical does 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 solidification Melting 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 ReactionsThe 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 The symbolic representation of a chemical substance in form of chemical substance in form of

assembled symbolsassembled symbolsMOLECULAR 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 hydrogen 2 hydrogen 1 oxygen1 oxygen

2 carbon,2 carbon,6 Hydrogen6 Hydrogen1 oxygen1 oxygen

Chemical FormulaChemical Formula

ExamplesExamples

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Chemical ChangeChemical Change

In, a chemical change the reacting substances change into new In, 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 metal For 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 O2 2 2Fe 2Fe22 O O33

iron iron oxygen oxygen iron oxideiron oxide

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Evidences of Chemical Evidences of Chemical ChangeChange

•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 Comparison of Some Chemical andChemical and

Physical ChangesPhysical ChangesChemical ChangesChemical Changes Physical ChangesPhysical ChangesRusting nailRusting nail Melting iceMelting iceBleaching a stainBleaching a stain Boiling waterBoiling waterBurning woodBurning wood cutting woodcutting woodTarnishing silverTarnishing silver Tearing paperTearing paperFermenting grapesFermenting grapes Breaking a glassBreaking a glassSouring 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 work is 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 energy When 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 continuous Particles 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).).

moleculesMagnified view of

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Energy in Chemical Reactions

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Heat Capacity of MatterHeatHeat is the energy associated with the is the energy associated with the

motion of particles in a substancemotion of particles in a substance

An energy change often shows that a chemical reaction is happening.

Sometimes heat energy is Sometimes heat energy is given outgiven out and the chemicals get and the chemicals get hothot. .

These reactions areThese reactions are called called Exothermic Exothermic reactions.reactions.

In other reaction, heat energy is In other reaction, heat energy is taken taken inin and the chemicals get and the chemicals get coldercolder. .

These are calledThese are called Endothermic reactions.Endothermic reactions.

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Exothermic and Endothermic Exothermic and Endothermic ReactionsReactions

Heat of Reaction:Heat of Reaction: Energy difference between Energy difference between

reactants and the productsreactants and the products Exothermic reaction:Exothermic reaction: Energy of the product is Energy of the product is lowerlower

than the reactant and heat is than the reactant and heat is given given outout..

Endothermic reaction:Endothermic reaction: Energy Energy of the product is of the product is higherhigher

than the reactant and heat must be than the reactant and heat must be absorbedabsorbed for products to form. for products to form.

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Exothermic and Endothermic Reactions Exothermic and Endothermic Reactions ExamplesExamples

Exothermic ReactionExothermic Reaction

CHCH44 + 2O + 2O2 2 CO CO22 + 2H + 2H22O + 213kcalO + 213kcal

Endothermic ReactionEndothermic Reaction

HH22 + I + I2 2 + 12 kcal of heat + 12 kcal of heat 2HI2HI

ReactionReaction Energy ChangeEnergy Change Heat in the Heat in the EquationEquation

Exothermic Heat releasedExothermic Heat released Product side Product side

Endothermic Heat absorbedEndothermic Heat absorbed Reactant side Reactant side

Heat absorbedHeat absorbed

MethaneMethane Heat released Heat 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 dressingHomogenized 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 or Classify 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 bar c. breaking a chocolate bar d. burning paperd. burning paper

4.4. Solve the following temperature conversions.Solve the following temperature conversions.

a. 37.0 a. 37.0 00C = ----------C = ----------00FF b. 65.3 b. 65.3 00F = ---------F = ---------00CC

c. 545K = ---------c. 545K = ---------00CC d. 224K = ----------d. 224K = ----------00CC

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. carbone. 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 summerb. 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 3CO 3CO22 + 4H + 4H22O + 531 kcalO + 531 kcal

b. the formation of “table” salt:b. the formation of “table” salt:2Na + Cl2Na + Cl22 2NaCl + 196 kcal 2NaCl + 196 kcal

c.c. decomposition of phosphorous pentachloride:decomposition of phosphorous pentachloride:PClPCl55 + 16 kcal + 16 kcal PClPCl33 + Cl + Cl22