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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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AP Photo/Darin Cummings
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.
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