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El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER OBSERVED PROPERTIES OF MATTER Matter exists in three distinct physical states:

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Presentation on theme: "El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER OBSERVED PROPERTIES OF MATTER Matter exists in three distinct physical states:"— Presentation transcript:

1 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 m density = = 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.

2 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER OBSERVED PROPERTIES OF MATTER MaterialDensity (gm/cm 3 ) Water at 4 o C Water at 20 o C0.998 Ice at 0 o C0.92 Gasoline0.70 Mercury13.6 Milk1.03 Magnesium1.7 Aluminum2.7 Copper Gold19.3 Air Carbon dioxide Carbon monoxide Hydrogen Helium Nitrogen mass m density = = d volume V golf balls / ping-pong balls

3 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER OBSERVED PROPERTIES OF MATTER 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

4 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES 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. 1 KE = ---- mv 2 2 E k = kinetic energy m = mass v = velocity (of the particle) Greek word κίνηση (kinesis) meaning "motion"

5 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE KINETIC MOLECULAR THEORY OF MATTER A model or a theory used to explain the behavior of matter in its various states. KINETIC ENERGY The energy a particle has as A result of its motion. 1 KE = ---- mv 2 2 POTENTIAL ENERGY The energy a particle has as A 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

6 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE SOLID STATETHE LIQUID STATE HIGH DENSITY DEFINITE SHAPE INDEFINITE SHAPE SMALL COMPRESSIBILITY VERY SMALL THERMAL EXPANSION SMALL THERMAL EXPANSION (DISRUPTIVE FORCES CAUSE VIBRATIONAL MOTION) (ONLY VIBRATIONAL MOTION INCREASES)

7 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE LOW DENSITY INDEFINITE SHAPE HIGH COMPRESSIBILITY MODERATE THERMAL EXPANSION

8 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS Nature of Gases - Properties Gases 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.

9 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS Kinetic Molecular Theory A 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).

10 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS physical characteristics typical units volume, V liters (L) pressure, p atmosphere (1 atm=1.015x10 5 N/m 2 ) temperature, T Kelvin (K) number of atoms or molecules, n mole (1 mol=6.022x10 23 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.

11 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS PRESSURE = FORCE PER UNIT AREA For gasses, usually related to atmospheric pressure. Schematic drawing of a simple mercury barometer with vertical mercury column and reservoir at base Evangelista Torricelli

12 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS Pressure Units pascal pascal(Pa) bar (bar) technical atmosphere (at) atmosphere (atm) torr (Torr) pound-force per square inch (psi) 1 Pa ≡ 1 N/m 2 10 − ×10 − ×10 − ×10 − ×10 −6 1 bar 100,000 ≡ 10 6 dyn/cm at 98, ≡ 1 kgf/cm atm 101, ≡ 1 atm torr ×10 − ×10 − ×10 −3 ≡ 1 Torr; ≈ 1 mmHg ×10 −3 1 psi 6, ×10 − ×10 − ×10 − ≡ 1 lbf/in 2 mmHg (blood pressure) mbar (atmospheric pressure a.k.a. p.s.i.

13 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS Celsius Fahrenheit Kelvin Temperature Conversion °C = (100/180) X (°F - 32) °F = (1.8 X °C) + 32 °K = °C °C = °K °K = [(100/180) X (°F - 32)] °F = [1.8 X (°K )] + 32 ABSOLUTE ZERO THE TEMPERATURE AT WHICH ALL MOTION STOPS 0 O K = O C

14 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS Boyle's Law: P 1 V 1 = P 2 V 2 (= const.) Charles' Law: V 1 /T 1 = V 2 /T 2 (= const.) Law of Gay-Lussac: P 1 /T 1 = P 2 /T 2 (= const.) 1662 Robert Boyle 1787 Jacques Chales 1809 Joseph Gay-Lussac

15 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS Boyle's Law: P 1 V 1 = P 2 V 2 (= const.) Charles' Law: V 1 /T 1 = V 2 /T 2 (= const.) Law of Gay-Lussac: P 1 /T 1 = P 2 /T 2 (= const.) PV The COMBINED GAS LAW : = k T 1662 Robert Boyle 1787 Jacques Chales 1809 Joseph Gay-Lussac

16 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE IDEAL GAS LAW Avogadro's Law: V 1 /n 1 = V 2 /n 2 (= const.) Boyle's Law: P 1 V 1 = P 2 V 2 (= const.) Charles' Law: V 1 /T 1 = V 2 /T 2 (= const.) Law of Gay-Lussac: P 1 /T 1 = P 2 /T 2 (= 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

17 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE IDEAL GAS LAW Avogadro's Law: V 1 /n 1 = V 2 /n 2 (= const.) Boyle's Law: P 1 V 1 = P 2 V 2 (= const.) Charles' Law: V 1 /T 1 = V 2 /T 2 (= const.) Law of Gay-Lussac: P 1 /T 1 = P 2 /T 2 (= 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 = nR T R = universal gas constant Equal volumes of different gases at the same temperature and pressure contain the same number of gas molecules.

18 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE IDEAL GAS LAW Ideal Gas Law: PV = nRT The number of moles ( n ) is equal to the mass ( m ) divided by the molar mass (M): PV The COMBINED GAS LAW : = k (= nR) T R = universal gas constant P = 1 atm T = 273 K STP (standard temperature and pressure) standard conditions V = 22.4 L (volume of 1 mol of any gas at STP)

19 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS R = V·P·T −1· n −1 R = L·atm·K −1 ·mol −1

20 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS R = V·P·T −1· n − cm 3 ·MPa·K −1 ·mol − L·kPa·K −1 ·mol − m 3 ·Pa·K −1 ·mol − × 10 7 erg·K− 1 ·mol − cm 3 ·bar·mol −1 ·K − L·mbar·K −1 ·mol − L·bar·K−1·mol− L·atm·K −1· mol − × 10 −5 m 3 ·atm·K −1· mol − cal·K −1· mol − L·mmHg·K −1· mol − L·Torr·K −1· mol − lbf·ft·K −1· g - mol − lbf·ft·°R −1· lb-mol − ft 3 ·psi· °R −1· lb-mol − ft 3 ·atm·°R −1· lb-mol − ft 3 ·mmHg·K −1· lb-mol −1 American units included R = L·atm·K −1 ·mol −1

21 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS 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 – O 2, N 2, etc.) the Ideal Gas Law can be applied successfully. PV = nRT m PV = -----RT M mRT M = 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. P T = P 1 + P 2 + P John Dalton

22 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER THE GASEOUS STATE; THE GAS LAWS Our respiratory systems are designed to maintain the proper oxygen concentration in the blood when the partial pressure of O 2 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 O 2 in ordinary air would be 0.42 atm; at a depth of 10 m ft (about 33 ft), the O 2 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 O 2. This can be achieved most simply by raising the nitrogen content, but high partial pressures of N 2 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

23 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER CHANGES IN STATE A change of state is the conversion of a substance from one physical form to another. All changes of state are physical changes. In a physical change the identity of the substance does not change. Four changes of state freezingmeltingvaporizationcondensation endothermic exothermic sublimation crystallization Which has more energy – gas or liquid? Which has more energy – liquid or solid? Which has more energy – gas or solid?

24 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER CHANGES IN STATE A change of state is the conversion of a substance from one physical form to another. All changes of state are physical changes. In a physical change the identity of the substance does not change. Four changes of state freezingmeltingvaporizationcondensation endothermic exothermic sublimation crystallization Which has more energy – gas or liquid? Which has more energy – liquid or solid? Which has more energy – gas or solid? Endothermic – energy is absorbed therefore the particles move faster, breaking the bonds Exothermic – energy is given off therefore particles move slower making them lock into place

25 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER CHANGES IN STATE vaporization Change from liquid to gas 2 types evaporation - occurs at the surface of a liquid below its boiling point Boiling – occurs throughout Boiling – occurs throughout a liquid when the temperature is at the boiling point endothermic Condensation – an exotermic process in which a gas or vapor is changed to a liquid or a solid.

26 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER 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).

27 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER CHANGES IN STATE Boiling Point Of Water Altitude in Feet Altitude in Meters Degrees F.Degrees C , , , 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 (116 o C, which corresponds to only 1.06 atm = 604 Torr) the cooking times must be increased by 33% in comparison to the standard 820 Torr.

28 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER CHANGES IN STATE Sublimation Change from solid directly to gas. The change of energy is endothermic. Melting Change from Change from solid to liquid Melting points can be used to identify a substance. Melting point is a The change of energy is endothermic because it absorbs energy thus the particles move away from one another Melting points can be used to identify a substance. Melting point is a characteristic property. The change of energy is endothermic because it absorbs energy thus the particles move away from one another Melting point The temperature at which a solid changes to a liquid; the solid and liquid have same vapor pressure. Decomposition a change in chemical composition that can result from heating. Total added heat (cal)

29 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER CHANGES IN STATE

30 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER 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 20 o C Substancec in J/gm K c in cal/gm K or Btu/lb F Molar C J/mol K Aluminum Bismuth Copper Brass Gold Lead Silver Tungsten Zinc Mercury Alcohol(ethyl) Water Ice (-10 C) Granite Glass

31 El Camino College Chemistry 21A Dr. Dragan Marinkovic THE STATES OF MATTER CHANGES IN STATE Heat 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.


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