1 Phases & Behavior of Matter Chs 13, 17, 2 Phases and Behavior of Matter Goals a. Understand the effects motion of atoms and molecules in chemical and physical processes. b. Compare and contrast atomic/molecular motion in solids, liquids, gases, and plasmas. c. Collect data and calculate the amount of heat given off or taken in by chemical or physical processes. d. Analyzing (both conceptually and quantitatively) flow of energy during change of state (phase). e. Apply concepts of the mole and Avogadro’s number to conceptualize and calculate molar volumes of gases. Solid Liquid Gas 3 Clip Kinetic Theory of Matter 1) All matter is composed of small particles (atoms). 2) These particles are in constant motion. 3) These particles are colliding with each other and the walls of their container. 4 Kinetic Energy • Kinetic Energy is the energy of motion. • Temperature is the measurement of the KE in an object. • So, the more KE the higher the temp. • As the particles in an object gain KE, the temperature goes up. 5 • • • • • • • • Solids Clip Particles are closely packed together. Most are geometric. (called Crystals) Particles are closely packed together. Most are geometric. (called Crystals) There are bonds between atoms/mol. Rigid shapes. Definite shape. Definite volume. Amorphous Solids 6 Amorphous Solids •Crystalline solids are arranged in fixed geometric patterns or lattices. • Lack highly “without form” ordered internal arrangement •Amorphous solids are solids with random • Melt over a unoriented molecules temperature range • Glass – Super-cooled liquid • Plastics • Some scientist classify them as “thick liquids” 7 Clip Liquids • Particles in a liquid have more KE than particles in a solid. • Liquid particles have enough KE to overcome the forces that hold them together. • The particles can now move past one another. (flow) • Definite volume • No Definite shape. Viscosity • Resistance to flow Viscosity 8 Clip Gases • Gas particles have more KE than liquid particles. • They have enough energy to break all bonds and escape the liquid state. • Particles are far apartno attractice forces between them 9 Gases • Motion of the molecules is random. • During collisions between particles, KE is transferred without loss of total energy. • No definite Shape • No definite Volume. 10 Gases are compressible 11 o Most common state of matter in the universe o Extremely high temperatures. o Contains positively and negatively charged particles Plasma Clip 12 Artificially produced plasmas Terrestrial plasmas •Those found in plasma displays, including TVs •Lightning •Inside fluorescent lamps (low energy lighting), neon signs •The ionosphere •The electric arc in an arc lamp, an arc welder or plasma torch •Plasma ball (sometimes called a plasma sphere or plasma globe) •The polar aurorae 13 o Force produced by high energy collisions strips electrons from atoms. o Sun, lighting bolts, neon and fluorescent tubes, auroras. ReviewClip Gasses exert pressure on the walls of their containers and objects around them. 14 • Pressure- measure in Pa • Atmospheric pressure- • Conversions- Units of pressure collision of atoms and molecules in the air with • (Q) What is object. 450kPA in mmHg and atm? -Standard pressure (atm) at 25˚C • Barometer- measure atm pressure – 4.4 atm – 3.4 x 103 mm Hg 15 16 Calculating molar volumes of gases • The molar volume is the volume occupied by one mole of ideal gas at STP. – Its value is: 22.414 L/mol ..so 1 mol of any gas has a volume of 22.4 L… @ STP 1 mol 22.4 L Standard Pressure = 1 atm Standard Temperature = 0 deg C (273 K) Goals: Apply concepts of the mole and Avogadro’s number to conceptualize and calculate molar volumes of gases 17 molar volumes of gases Practice Problems 2 H2O2 (l) ---> 2 H2O (g) + O2 (g) Decompose 1.1 g of H2O2 in a flask with a volume of 2.50 L. What is the volume of O2 at STP? 1.1 g H2O2 1 mol H2O2 1 mol O2 22.4 L O2 34 g H2O2 2 mol H2O2 1 mol O2 = 0.36 L O2 at STP Cool Fact: Bombardier beetle uses decomposition of hydrogen peroxide to defend itself. 18 molar volumes of gases 1. What volume is occupied by 10 moles of ammonia, NH3, at standard conditions? 224 liters 2. What is the volume occupied by 40 grams of argon gas (Ar) at standard conditions? 22.4 liters 3. What volume, in liters, is occupied by 1.5 x 1023 atoms of argon gas (Ar) at STP? 5.6 liters 4. What volume would be occupied by 120 grams of argon gas (Ar) at standard conditions? 67.2 liters 5. What volume will 0.750 moles of nitrogen gas occupy at STP? 16.8 L N2 6. How many moles are contained in 2.500 liters of methane (CH4) at STP? 0.112 mol CH 4 19 C3H8 (g) + 5 O2 (g) 3 CO2 (g) + 4 H2O (g) 1. What mass of H2O is produced if 50.0 % of CO2 is produced at STP? 2. How many moles of gas are present in 11.2 L at STP? How many molecules? 3. How many molecules of O2 are present in 56.0L at STP? 56L 1 mol 22.4 L 6.022 x 1023 molecules 1 mol = 1/10 mole 4. A sample of carbon dioxide gas (CO2) contains 6 x 1022 molecules. How many moles of carbon dioxide 20 21 Measuring Heat • Heat is a form of energy, and it is measure in Joules or Calories. • Calorie; the quanity of heat needs to raise the temperature of 1g of pure water 1˚C. • Note: Dietary Calorie is actually 1kcal. 22 23 Specific Heat • Adding Energy to a material Causes the… – Temperature to go up. • Taking energy away from a substance causes the temp. to… – Go down! Specific means “certain” Which would heat up faster? The aluminum or the plastic? • Have you ever noticed that on a hot summer day the pool is cooler than the hot cement? • OR maybe that the ocean is cooler than the hot sand? • Why? The sun has been beating down on (delivering energy to) both of them for the same amount of time.....same amount of energy. • It takes more thermal energy to raise the temperature of water 24 that it does the cement! 25 26 27 Specific Heat • The amount of energy required to raise the temperature of a material (substance). • It takes different amts of energy to make the same temp change in different substances. • We call the amt required: Specific Heat! 28 Every materials requires a different amount of energy to change its temperature. (Cp ) Cp Stands for “Heat Capacity” Note: The lower the number, the FASTER the material heats up….and cools down 29 Specific Heat of water • The Cp is high because H2O mols. form strong bonds w/each other. • It takes a lot of energy to break the bonds so that the the molecules can then start to move around faster (HEAT UP). 18 30 Calculating Amount of Heat p The Greek letter Δ means “change in” 31 EXAMPLE : • What amount of heat is required to raise the temperature of 85.9 kg of water by 7C? The specific heat of water is 4.184 J/gC. • Mass = 85.9kg • Q = ? • Δt = 7° • Cp = 4.184 J/g-C? • Q =m x Cp x Δt • Q= (85.9kg)(4.184 J/g-C)(7°C) • Q= 2515.8 J • (WHAT DOES THAT MEAN?) 32 Can you get a negative “Q” • Q =m x Cp x Δt • Yes. • If the object is LOSING heat. 33 Specific Heat Practice with a friend…. 1. How much heat must be absorbed by 375 grams of 3.9 x 104 J water to raise its temperature by 25° C? 2. How much energy (in calories and in Joules) will it take to raise the temperature of 75.0 g of water from 20.0 2630 cal and 1.1 x 10 4 J to 55.0 oC? 3. What is the heat in Joules required to raise the temperature of 25 grams of water from 0 °C to 100 °C? What is the heat in calories? 10450 J or 2500 calories 4. It takes 487.5 J to heat 25 grams of copper from 25 °C to 75 °C. What is the specific heat in Joules/g·°C? 0.39 J/g·°C. 5. 350 J are released as ice ( Specific Heat = 2.1 J / (g oC) ) cools from - 5.0 oC to -32 oC. What is the mass of ice? 6.2 g 34 35 Changing State 36 37 38 Sublimation • Some substances go from the solid state directly to the gaseous state. This happens when a substance was below it freezing point and is suddenly moved to a location where it is above its boiling point • EX: CO2 39 Boiling Point and Pressure • Water boils at about 95 degrees C in Denver and higher than 100 degrees C in a pressure cooker. 40 •It takes energy to cause phase changes( soild-liq-gas) •Removal of energy (gas-liq-solid) Phase changes do not change the substance Clip 41 42 • The amount of energy required for a substance to go from a solid to a liquid is called the HEAT OF FUSION. • (EX) it takes 334,000 Joules of energy to melt 1 kg of ice. No temperature change. 0°C 0°C NO TEMP CHANGE 43 • The amount of energy required to change a liquid to a gas is called the …Heat of Vaporization • EX: It takes 2,260,000 Joules of energy to vaporize 1 kg of water. 100 °C 100 °C NO TEMP CHANGE 44 Practice Problems Information: H20 Heat of Fusion (hf) = 334 J/g Heat of vaporization (hv) =2260 J/g 1. What is the heat in Joules required to convert 25 grams of water into steam? What is the heat in calories? 56425 J, 13,500 cal 2. What is the heat in Joules required to melt 25 grams of ice? What is the heat in calories? 8350 Joules or 2000 cal 3. How much energy would be required to melt 15.0 g of ice at 0 oC? 5.01 KJ 4. How much energy would it take to boil 36.0 g of water at 100 oC? 81.4 KJ 45 Combination Problems…. You can do this • How much energy would it take to melt 30.0 g of ice at 0 oC and warm the resulting liquid to 35.0 oC? – 14.4 KJ • How much energy would it take to warm 30.0 g of water at 35 oC to the boiling point and boil all the liquid away? – 76 KJ • How much energy would be reqired to melt 10.0 g of ice at 0 oC, warm the resulting liquid to 100 oC, and change it to steam at 100 oC? – 30.1 KJ 46 • Phase depends not only on temp. but also pressure. • The triple point of a substance is the temp. and pressure at which the three phases of that substance coexist 47 Phase depends not only on temp. but also pressure. 48 When heat is added to most materials they expand Thermal Expansion • When objects are heated, they expand. • When they are cooled, they contract. • Video Clip 49 Thermal Expansion • Thermometers: Work because of thermal expansion. Typical expansion joints on a steel span bridge. 50 51 52 Gases exert pressure on their container Pressure (Pa)= Force (N) Area (M2) The Pascal (Pa) is the SI • Pressure: The amt of force exerted per unit of area. • Gases exert pressure by colliding with “things.” 53 1.Other particles of gas 2.Sides of the container 3.Objects within the area of the gas, like you. Clip 54 Boyle’s and Charles’ law • Both deal with gases. • Boyle’s Law – As the volume decreases, the pressure increases. • Charles’ Law – As the temperature decrease, the volume of a gas decreases. 55 Boyle’s Law • Relationship between volume and pressure. You tube Clip P1V1 = P2V2 56 Boyle’s Law P1V1 = P2V2 If you decrease the volume, the pressure will increase ( no Δt) 57 Charles’ Law • Relationship between volume and temperature. In theory there is a temperature in which gases ceases to have volume. This temp. is referred to as absolute zero. Absolute Temp. Scale T (K) = °C + 273.15 K 58 Charles’ Law If you increase the temperature, the volume will increase 59 Gay-Lussac’s Law If n and V are constant, then P α T P and T are directly proportional. • If one temperature goes up, the pressure goes up! Joseph Louis GayLussac (1778-1850) 60 • PHET Gas Properties simulation • PHET States of Matter simulation 61 The End