el camino college chemistry 21a dr. dragan marinkovic the states of matter observed properties of...

El Camino College Chemistry 21A Dr. Dragan Marinkovic

THE STATES OF MATTER

OBSERVED PROPERTIES OF MATTER

Matter exists in three distinct physical states:

GAS

LIQUID and

SOLID

mass mdensity = ------------ = ------ volume V

PROPERTIES :

shape depends on the physical state of matter

compressibility is the change in volume of a sample resulting from a pressure change acting on the sample.

thermal expansion is the change in volume of a sample resulting from a change in temperature of the sample.




Material Density(gm/cm3)

Water at 4oC 1.0000Water at 20oC 0.998Ice at 0oC 0.92Gasoline 0.70Mercury 13.6Milk 1.03Magnesium 1.7Aluminum 2.7Copper 8.3-9.0Gold 19.3Air 0.001293Carbon dioxide 0.001977Carbon monoxide 0.00125Hydrogen 0.00009Helium 0.000178Nitrogen 0.001251

mass mdensity = ------------ ------ = d

volume V

golf balls / ping-pong balls




Gases take the shape of a container and fully fill the

(closed) container – i.e. have the same volume as the inside of

the container.

Solids retain the shape regardless of the size or shape of the container they are in.

Liquids take the shape of a container, but retain their volume.

shape depends on the physical state of matter



THE KINETIC MOLECULAR THEORY OF MATTER


A model or a theory used to explain the behavior of matter in its various states.

THE POSTULATES OF THE KINETIC MOLECULAR THEORY

1. Matter is composed of tiny particles called molecules.2. The particles are in constant motion and therefore posses kinetic energy (KE).3. The particles posses potential energy as a result of attracting or repelling each other. 4. The average particle speed increases as the temperature increases.5. The particles transfer energy from one to another during collisions in which no net

energy is lost from the system.

1KE = ---- mv2

2

Ek = kinetic energym = massv = velocity (of the particle)

Greek word κίνηση (kinesis) meaning "motion"





A model or a theory used to explain the behavior of matter in its various states.

KINETIC ENERGY

The energy a particle has asA result of its motion.

1KE = ---- mv2

2

POTENTIAL ENERGY

The energy a particle has asA result of attractive or repulsive forces acting on it.

COHESIVE FORCE

The attractive force between particles; it is associated with potential energy.

DISRUPTIVE FORCE

The force resulting from particles motion; it is associated with kinetic energy.

macromolecular examples:gravitation; magnetic energy

THE STATE OF MATTER

DEPENDS ON



THE SOLID STATE THE LIQUID STATE

HIGH DENSITY

DEFINITE SHAPE INDEFINITE SHAPE

SMALL COMPRESSIBILITY

VERY SMALL THERMAL EXPANSION

SMALL THERMAL EXPANSION

(DISRUPTIVE FORCES CAUSEVIBRATIONAL MOTION)

(ONLY VIBRATIONALMOTIONINCREASES)



THE GASEOUS STATE

LOW DENSITY

INDEFINITE SHAPE

HIGH COMPRESSIBILITY

MODERATE THERMAL EXPANSION



THE GASEOUS STATE; THE GAS LAWS

Nature of Gases - PropertiesGases are compressible. Gases have low densities. (typically 2x10-3 g/mL) Gases mix thoroughly. Gases fill a container uniformly. A gas exerts pressure uniformly on all sides of a container.Gases have moderate thermal expansion.

Disruptive forces overcome cohesive forces between particles.




Kinetic Molecular TheoryA gas is composed of very small particles widely spaced. A gas is composed mostly of empty space. The molecules of a gas are in rapid, random motion, colliding with each other and the sides of the container. Pressure is a result of these collisions. All collisions involving gas molecules are elastic (non-elastic - ball bouncing gets lower and lower each time). Gas molecules have negligible attractive (or repulsive) forces between them. The temperature of a gas is related to the average kinetic energy of the gas molecules. (At the same temp. diff. gases have the same average KE).




physical characteristicsphysical characteristics typical unitstypical units

volumevolume, V, V liters (L)liters (L)

pressurepressure, p, p atmosphere (1 atm=1.015x10atmosphere (1 atm=1.015x1055N/mN/m22))

temperaturetemperature, T, T Kelvin (K)Kelvin (K)

number of atoms or moleculesnumber of atoms or molecules, n, n mole (1 mol=6.022x10mole (1 mol=6.022x102323 atoms or molecules) atoms or molecules)

Physical Characteristics of Gases

GAS LAW is a mathematical relationship that describes

behavior of gases as they are mixed, subjected to pressure or temperature changes, or allowed

to diffuse.




PRESSURE = FORCE PER UNIT AREAFor gasses, usually related to atmospheric pressure.

Schematic drawing of a simple mercury barometer with vertical mercury column and reservoir at base

Evangelista Torricelli




Pressure UnitsPressure Units

pascalpascal(Pa)(Pa)

barbar(bar)(bar)

technical technical atmosphereatmosphere

(at)(at)atmosphereatmosphere

(atm)(atm)torrtorr

(Torr)(Torr)

pound-force perpound-force persquare inchsquare inch

(psi)(psi)

1 Pa1 Pa ≡ ≡ 1 N/m1 N/m22 1010−5−5 1.0197×101.0197×10−5−5 9.8692×109.8692×10−6−6 7.5006×107.5006×10−3−3 145.04×10145.04×10−6−6

1 bar1 bar 100,000100,000 ≡ ≡ 101066 dyn/cm dyn/cm22 1.01971.0197 0.986920.98692 750.06750.06 14.503774414.5037744

1 at1 at 98,066.598,066.5 0.9806650.980665 ≡ ≡ 1 kgf/cm1 kgf/cm22 0.967840.96784 735.56735.56 14.22314.223

1 1 atmatm 101,325101,325 1.013251.01325 1.03321.0332 ≡ ≡ 1 atm1 atm 760760 14.69614.696

1 1 torrtorr 133.322133.322 1.3332×101.3332×10−3−3 1.3595×101.3595×10−3−3 1.3158×101.3158×10−3−3 ≡ ≡ 1 Torr; 1 Torr;

≈ 1 mmHg≈ 1 mmHg 19.337×1019.337×10−3−3

1 psi1 psi 6,894.766,894.76 68.948×1068.948×10−3−3 70.307×1070.307×10−3−3 68.046×1068.046×10−3−3 51.71551.715 ≡ ≡ 1 lbf/in1 lbf/in22

mmHg (blood pressure)mbar (atmospheric pressure

a.k.a. p.s.i.




Celsius

Fahrenheit

Kelvin

Temperature Conversion

°C = (100/180) X (°F - 32)°F = (1.8 X °C) + 32°K = °C + 273.15°C = °K - 273.15°K = [(100/180) X (°F - 32)] + 273.15°F = [1.8 X (°K - 273.15)] + 32

ABSOLUTE ZEROTHE TEMPERATURE AT WHICH ALL MOTION STOPS 0OK = -273.15OC




Boyle's Law: P1V1 = P2V2 (= const.)

Charles' Law: V1/T1 = V2/T2 (= const.)

Law of Gay-Lussac: P1/T1 = P2/T2 (= const.)

1662 Robert Boyle

1787 Jacques Chales

1809 Joseph Gay-Lussac







PV

The COMBINED GAS LAW : ---------- = k T

1662 Robert Boyle

1787 Jacques Chales

1809 Joseph Gay-Lussac



THE IDEAL GAS LAW

Avogadro's Law: V1/n1 = V2/n2 (= const.)




1811 Amadeo Avogadro

The number of moles (n ) is equal to the mass (m ) divided by the molar mass (M):

PV

The COMBINED GAS LAW : ---------- = k T



THE IDEAL GAS LAW

Avogadro's Law: V1/n1 = V2/n2 (= const.)




1811 Amadeo Avogadro


PV

The COMBINED GAS LAW : ---------- = k = nR T

R = universal gas constant

Equal volumes of different gases at the same temperature and pressure contain the same number of gas molecules.



THE IDEAL GAS LAW

Ideal Gas Law: PV = nRT


PV

The COMBINED GAS LAW : ---------- = k (= nR) T

R = universal gas constant

P = 1 atmT = 273 K STP (standard

temperature and pressure)

standard conditions

V = 22.4 L (volume of 1 mol of any gas at STP)




R = V·P·T−1·n−1 R = 0.0820574587 L·atm·K−1·mol−1




R = V·P·T−1·n−1

8.314472 cm3·MPa·K−1·mol−1 8.314472 L·kPa·K−1·mol−1 8.314472 m3·Pa·K−1·mol−1 8.314472 × 107 erg·K−1·mol−1

83.14472 cm3·bar·mol−1·K−1 83.14472 L·mbar·K−1·mol−1 0.08314472 L·bar·K−1·mol−1

0.0820574587 L·atm·K−1·mol−1

8.20574587 × 10−5 m3·atm·K−1·mol−1 1.987 cal·K−1·mol−1

62.36367 L·mmHg·K−1·mol−1

62.36367 L·Torr·K−1·mol−1

6.132440 lbf·ft·K−1·g-mol−1 6.132440 lbf·ft·K−1·g-mol−1

1545.349 lbf·ft·°R−1·lb-mol−1

10.73159 ft3·psi· °R−1·lb-mol−1

0.7302413 ft3·atm·°R−1·lb-mol−1

998.9701 ft3·mmHg·K−1·lb-mol−1

American units included

R = 0.0820574587 L·atm·K−1·mol−1




Ideal gases do NOT exist. However, under normal conditions (moderate temperatures and pressures) for the most gases (such as monoatomic gases – noble gases and nonpolar molecular gases – O2, N2, etc.) the Ideal Gas Law can be applied successfully.

PV = nRT

mPV = -----RT M

mRTM = ------- PV

molecular weight

Dalton’s Law of Partial Pressures the total pressure of a gas in a system is the sum of the partial pressures of each component gas.

PT = P1 + P2 + P3 + ....

1801 John Dalton




Our respiratory systems are designed to maintain the proper oxygen concentration in the blood when the partial pressure of O2 is 0.21 atm, its normal sea-level value. Below the water surface, the pressure increases by 1 atm for each 10.3 m increase in depth; thus a scuba diver at 10.3 m experiences a total of 2 atm pressure pressing on the body. In order to prevent the lungs from collapsing, the air the diver breathes should also be at about the same pressure.But at a total pressure of 2 atm, the partial pressure of O2 in ordinary air would be 0.42 atm; at a depth of 10 m ft (about 33 ft), the O2 pressure of 0.4 atm would be far too high for health. For this reason, the air mixture in the pressurized tanks that scuba divers wear must contain a smaller fraction of O2. This can be achieved most simply by raising the nitrogen content, but high partial pressures of N2 can also be dangerous, resulting in a condition known as nitrogen narcosis. The preferred diluting agent for sustained deep diving is helium, which has very little tendency to dissolve in the blood even at high pressures.

Scuba Diving



CHANGES IN STATE

A change of state is the A change of state is the conversion of a substance from conversion of a substance from one physical form to another.one physical form to another.All changes of state are physical changes.All changes of state are physical changes.In a physical change the identity of the In a physical change the identity of the substance does not change.substance does not change.

Four changes of Four changes of statestate

freezingfreezingmeltingmeltingvaporizationvaporizationcondensationcondensation

endothermic

exothermic

sublimation crystallization

Which has more energy – gas or liquid?Which has more energy – gas or liquid?

Which has more energy – liquid or solid?Which has more energy – liquid or solid?

Which has more energy – gas or solid?Which has more energy – gas or solid?



CHANGES IN STATE

A change of state is the A change of state is the conversion of a substance from conversion of a substance from one physical form to another.one physical form to another.All changes of state are physical changes.All changes of state are physical changes.In a physical change the identity of the In a physical change the identity of the substance does not change.substance does not change.

Four changes of Four changes of statestate

freezingfreezingmeltingmeltingvaporizationvaporizationcondensationcondensation

endothermic

exothermic

sublimation crystallization

Which has more energy – gas or liquid?Which has more energy – gas or liquid?

Which has more energy – liquid or solid?Which has more energy – liquid or solid?

Which has more energy – gas or solid?Which has more energy – gas or solid?

Endothermic – energy is absorbed Endothermic – energy is absorbed therefore the particles move faster, therefore the particles move faster, breaking the bondsbreaking the bonds

Exothermic – energy is given off Exothermic – energy is given off therefore particles move slower therefore particles move slower making them lock into placemaking them lock into place



CHANGES IN STATE

vaporizationvaporization

Change from liquid to gasChange from liquid to gas2 types2 types

evaporationevaporation - occurs - occurs at the at the surfacesurface of a liquid below its of a liquid below its boiling pointboiling pointBoiling Boiling – occurs – occurs throughoutthroughout a liquid when the temperature is at the boiling point

endothermicCondensation – an exotermic process in which a gas or vapor is changed to a liquid or a solid.



CHANGES IN STATE

water vapor presure

Vapor pressure The pressure exerted by vapor hat is in equilibrium with liquid.It depends on the nature of the liquid (molecular polarity, mass, etc.) and the temperature of the liquid.

When vapor pressure reaches 760 Torr (1 atm) the liquid starts to boil,i.e. the liquid reached the boiling point.

Normal or standard boiling point is the temperature at which the vapor pressure of a liquid is equal to 1 atm (760 Torr).



CHANGES IN STATE

Boiling Point Of Water

Altitude inFeet

Altitude inMeters

Degrees F. Degrees C.

0 0 212.0 100.0

500 152 211.0 99.4

1000 305 210.0 98.9

2000 610 208.2 97.9

3000 914 206.2 96.8

4000 1219 204.4 95.8

5000 1524 202.6 94.8

6000 1829 200.7 93.7

7000 2134 198.7 92.6

8000 2438 196.9 91.6

10,000 3048 194.0 90.0

12,500 3810 189.8 87.7

14,000 4267 187.3 86.3

For every 1000 ft above 2000 ft elevation, increase the cooking time by 5%.

A standard pressure cooker operating at 820 Torr (1.078 atm), rises the boiling point of water to 250°F (121°C) at sea level. At 240°F (116oC, which corresponds to only 1.06 atm = 604 Torr) the cooking times must be increased by 33% in comparison to the standard 820 Torr.



CHANGES IN STATE

SublimationSublimationChange from solid directly to gas.Change from solid directly to gas.The change of energy is endothermic.The change of energy is endothermic.

MeltingMelting Change from Change from solid to liquidMelting points can be used to identify a Melting points can be used to identify a substance. Melting point is a substance. Melting point is a characteristic property. The change of energy is The change of energy is endothermic because it absorbs energy thus endothermic because it absorbs energy thus the particles move away from one anotherthe particles move away from one another

Melting point Melting point The temperature at which a The temperature at which a solid changes to a liquid; solid changes to a liquid; the solid and liquid have the solid and liquid have same vapor pressure.same vapor pressure.

Decomposition a change in chemical composition that can result from heating.

Total added heat (cal)



CHANGES IN STATE



CHANGES IN STATE

The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius

Specific heats and molar heat capacities for various substances at 20oC

Substance c in J/gm Kc in cal/gm K orBtu/lb F

Molar CJ/mol K

Aluminum 0.900 0.215 24.3

Bismuth 0.123 0.0294 25.7

Copper 0.386 0.0923 24.5

Brass 0.380 0.092 ...

Gold 0.126 0.0301 25.6

Lead 0.128 0.0305 26.4

Silver 0.233 0.0558 24.9

Tungsten 0.134 0.0321 24.8

Zinc 0.387 0.0925 25.2

Mercury 0.140 0.033 28.3

Alcohol(ethyl) 2.4 0.58 111

Water 4.186 1.00 75.2

Ice (-10 C) 2.05 0.49 36.9

Granite .790 0.19 ...

Glass .84 0.20 ...



CHANGES IN STATEHeat of Fusion

The energy required to change a gram of a substance from the solid to the liquid state without changing its temperature is

commonly called it's "heat of fusion". This energy breaks down the solid bonds, but leaves a significant amount of energy associated with the intermolecular forces of the liquid state.

Heat of Vaporization

The energy required to change a gram of a liquid into the gaseous state at

the boiling point is called the "heat of vaporization". This energy breaks down the intermolecular attractive forces, and also must provide the energy necessary to expand the gas (the PDV work). For an ideal gas , there is no longer any potential energy associated with intermolecular forces. So the internal energy is entirely in the molecular kinetic energy.

el camino college chemistry 21a dr. dragan marinkovic the states of matter observed properties of...

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