States of MatterStates of MatterTheir Nature & BehaviorTheir Nature & Behavior

A Gas A Gas - Has massHas mass- Compresses easilyCompresses easily- Fills containersFills containers- Moves through others w/easeMoves through others w/ease- Exerts pressureExerts pressure- Pressure depends on its temperaturePressure depends on its temperature

Assumption #1: Assumption #1: Small particles with mass• Explains increase in mass of inflated ball

Assumption #2: Assumption #2: Particles separated by large distances• Explains compressibility & low density

Assumption #3: Assumption #3: Particles in constant, rapid motion• Explains filling container• Particles perfectly ELASTICELASTIC so no kinetic energy

lost in collisions

1. Gas consists of very small particles each with mass

2. Distance separating gas particles is large

3. Gas particles in constant, rapid, random motion

4. Collisions are random & perfectly elastic

5. Average kinetic energy of particles depends on temperature

6. Gas particles exert no force on one another

Based on 4 factors:Based on 4 factors:

1.1. Amount of gas (n)Amount of gas (n)

2.2. Volume (V)Volume (V)

3.3. Temperature (T)Temperature (T)• Measured in degrees Kelvin (Measured in degrees Kelvin (ooK) K)

4.4. Pressure (P)Pressure (P)• Measured in atmospheres (atm) or Measured in atmospheres (atm) or

millimeters of Mercury (mm Hg)millimeters of Mercury (mm Hg)

STPSTP = 273 = 273ooK and 1atm or 760mm HgK and 1atm or 760mm Hg

Boyle’s Law (Pressure & Volume)Boyle’s Law (Pressure & Volume)• Pressure & Volume are inversely

proportional to each other• As one goes up, the other goes down

PP11VV11=P=P22VV22

Charles’s Law (Temperature & Volume)Charles’s Law (Temperature & Volume)• Temperature & volume are directly

proportional to each other• As one goes up, so does the other

VV11TT22=V=V22TT11

Avogadro’s Law (Volume & Particle #)Avogadro’s Law (Volume & Particle #)• Equal volumes of gases at same temp &

pressure have equal # of particles

Dalton’s Law (Partial Pressures)Dalton’s Law (Partial Pressures)• Sum of partial pressures is equal to total

pressure of a gas mixture

IDEAL GAS LAWIDEAL GAS LAW

PV = nRTPV = nRT

• State of substances @ room temp depends on strength of attraction between particles

• Solids – STRONG• Liquids – Medium• Gas – WEAK or nonexistent

InterIntermolecular molecular forcesforces

Inter = betweenIntermolecular forces – between molecules

Intra = withinIntramolecular forces – ionic & covalent bonds

Dispersion ForceDispersion Force• Attraction between induced dipolesAttraction between induced dipoles(temporary changes from spherical shape of an atom

can produce temporary dipole which then induces one nearby into a temporary dipole)

• Boiling points of liquids measures Boiling points of liquids measures strength of dispersion forcestrength of dispersion force

• Gets larger as atomic mass increasesGets larger as atomic mass increases

Dipole-Dipole ForcesDipole-Dipole Forces• Formed between polar molecules with Formed between polar molecules with

permanent dipolespermanent dipoles

Hydrogen BondingHydrogen Bonding• Strong intermolecular forceStrong intermolecular force• Formed between polar molecules Formed between polar molecules

where covalent bonds exist between H where covalent bonds exist between H and F,O or N which have high and F,O or N which have high electronegativities.electronegativities.• Ex: WaterEx: Water

ViscosityViscosity• Friction or resistance to motion of

molecules moving past one another• Stronger IMF’s = more viscosity• Increases as temperature decreases

“Slow as molasses in January…”

Surface TensionSurface Tension• Imbalance of forces @ surface making

it behave solid-like• Strong for water

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Specific HeatSpecific Heat• Amount of heat absorbed or lost for 1g

of substance to change 1oC• Water has high specific heat – it resists

temperature change• Keeps earth within viable temperature

limits.

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Density of IceDensity of Ice• Solid water is less dense than its liquid

because as hydrogen bonds freeze, they force molecules further apart

• In large bodies of water, top layer of ice actually insulates water below

• 4oC is water at its most dense

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Universal SolventUniversal Solvent• Water dissolves many materials creating

aqueous solutions (water is solvent, what’s being dissolved is solute)

• This property is the direct result of water’s polar structure• HydrophilicHydrophilic – substances attracted to

water• HydrophobicHydrophobic – repel water (or not

attracted)

Organisms rely on water’s high heat of vaporization to remove body heat

High Heat of VaporizationHigh Heat of Vaporization

Evaporative CoolingEvaporative Cooling

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Nature of SolidsNature of Solids

Crystalline• Molecules in highly ordered, repeating

pattern• Ex: salt, sugar, gemstones, snow

Amorphous• Appear solid but are not crystalline• Behave as supercooled liquids

• Ex: glass, rubber, wax

Properties of SolidsProperties of Solids

Physical Properties, such as• Electrical conductivity• Melting point• Hardness

depend on• Types of particles• Strengths of attractive forces between

particles

Types of SolidsTypes of SolidsMetallic• Excellent electrical & thermal conductors

• Ex: Al, Cu, Ag, Fe

Molecular• Lower melting point; poor conductors

• Ex: Organic compounds, water, carbon dioxide

Ionic• Brittle; high melting point; poor conductors

• Ex: Typical salts, NaCl

Covalent Network• High melting points

• Ex: diamond form of carbon

SolutionsSolutions

Types of Solutions

1.1. SolidSolid• Metal alloys

2.2. GaseousGaseous• Air

3.3. LiquidLiquid• Aqueous solution

Concentration of SolutionsConcentration of Solutions

• amount of solute in a given amount of solvent

Molarity – number of moles per liter

Molarity = Moles of solute

L of solution

Acids & BasesAcids & Bases

• In pure water, the concentration of H+ and OH- ions is equal

• When acids or bases are added to water, these concentrations change quickly

• pH is a measure of hydrogen ion concentration on a scale between 0-14

10–1

H+ IonConcentration

Examples of Solutions

Stomach acid, Lemon juice

1

pH100 Hydrochloric acid0

10–2 2

10–3 Vinegar, cola, beer3

10–4 Tomatoes4

10–5 Black coffee, Rainwater5

10–6 Urine, Saliva6

10–7 Pure water, Blood7

10–8 Seawater8

10–9 Baking soda9

10–10 Great Salt Lake10

10–11 Household ammonia11

10–12 Household bleach12

10–13 Oven cleaner13

10–14 Sodium hydroxide14

AcidsAcids• Chemical compounds that donate H+ ions

as they dissociate in solution (Bronsted-Lowry definition)

• EX: HCl H+ Cl- • The more acidic a solution,

• The higher the H+ concentration• The lower the pH

• Taste sour• pH < 7

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BasesBases

• Compounds that accept H+ ions and remove them from solution (Bronsted-Lowry definition)

• Some donate OH- ions• The more basic a solution,

• The lower its H+ concentration• The higher its pH value

• Taste bitter

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BuffersBuffers

• Substances that resist changes in pH• Many of these in the body since even

minor changes can be life threatening• EX: blood ph is 7.4

• CO2 (carbonic acid when dissolved in water) donates H+ to lower pH

• HCO3 (bicarbonate) binds excess H+

to raise pH

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NeutralizationNeutralization• When bases and acids of

similar strength are combined, the pH of the solution will approach neutral (pH 7)

• Water is often a product of a neutralization reaction.