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Properties of Matter Chapter 4

Properties of Matter Chapter 4. Chapter 4 - Properties of Matter. 4.1 Properties of Substances. 4.6 Heat: Quantitative Measurement. 4.2 Physical Changes. 4.7 Energy in Chemical Changes. 4.3 Chemical Changes. 4.8 Conservation of Energy. 4.4 Conservation of Mass. 4.5 Energy.

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Properties of Matter Chapter 4

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  1. Properties of MatterChapter 4

  2. Chapter 4 - Properties of Matter 4.1 Properties of Substances 4.6 Heat: Quantitative Measurement 4.2 Physical Changes 4.7 Energy in Chemical Changes 4.3 Chemical Changes 4.8 Conservation of Energy 4.4 Conservation of Mass 4.5 Energy

  3. Properties of a Substance • A property is a characteristic of a substance. • Each substance has a set of properties that are characteristic of that substance and give it a unique identity. • Can be classified as either physical or chemical

  4. Properties of a Substance Physical Properties • The inherent characteristics of a substance that are determined without changing its composition. • Examples: • taste • color & odor • physical state • melting point • boiling point • density

  5. Physical Properties

  6. Chemical Properties Describe the ability of a substance to form new substances, either by reaction with other substances or by decomposition.

  7. Chemical Properties of Chlorine • It will not burn in oxygen. • It will support the combustion of certain other substances. • It can be used as a bleaching agent. • It can be used as a water disinfectant. • It can combine with sodium to form sodium chloride.

  8. Physical Changes • Changes in physical properties (such as size shape and density) or changes in the state of matter without an accompanying change in composition. • Examples: • tearing of paper • change of ice into water • change of water into steam • heating platinum wire • No new substances are formed.

  9. Chemical Changes In a chemical change new substances are formed that have different properties and composition from the original material.

  10. Formation of Copper(II) Oxide Heating a copper wire in a Bunsen burner causes the copper to lose its original appearance and become a black material. The black material is a new substance called copper(II) oxide. Copper is 100% copper by mass. Copper (II) oxide is: 79.94% copper by mass 20.1% oxygen by mass. The formation of copper(II) oxide from copper and oxygen is a chemical change. The copper (II) oxide is a new substance with properties that are different from copper. Heating a copper wire in a Bunsen burner causes the copper to lose its original appearance and become a black material.

  11. Formation of Copper(II) Oxide Neither Cu nor O2 contains Cu2+ or O2- A chemical change has occurred. Copper(II) oxide is made up of Cu2+ and O2- 4.2

  12. Decomposition of Water The composition and physical appearance of hydrogen and oxygen are different from water. The hydrogen explodes with a pop upon the addition of a burning splint. The oxygen causes the flame of a burning splint to intensify. Water is decomposed into hydrogen and oxygen by passing electricity through it. They are both colorless gases. But the burning splint is extinguished when placed into the water sample.

  13. Chemical Equations products reactant yields Water decomposes into hydrogen and oxygen when electrolyzed.

  14. 2H2O 2H2 O2 reactant yields products Chemical symbols can be used to express chemical reactions Water decomposes into hydrogen and oxygen when electrolyzed.

  15. heat product yield reactants Copper plus oxygen yields copper(II) oxide.

  16. 2Cu O2 2Cu2O product yield reactants Copper plus oxygen yields copper(II) oxide. heat

  17. Conservation of Mass No change is observed in the total mass of the substances involved in a chemical change.

  18. 46.0 g 32.1 g mass reactants = Conservation of Mass sodium + sulfur  sodium sulfide 78.1 g → 78.1 g reactant 78.1 g product mass products

  19. Energy Energy is the capacity to do work • Potential Energy Energy that an object possesses due to its relative position. • Kinetic Energy Energy matter possesses due to its motion.

  20. Types of Energy • mechanical • chemical • electrical • heat • nuclear • radiant

  21. increasing potential energy 50 ft increasing potential energy 20 ft The potential energy of the ball increases with increasing height.

  22. Potential Energy Stored energy • The heat released when gasoline burns is associated with a decrease in its chemical potential energy. • The new substances formed by burning have less chemical potential energy than the gasoline and oxygen. • Gasoline is a source of chemical potential energy.

  23. Moving bodies possess kinetic energy. • The flag waving in the wind.

  24. Moving bodies possess kinetic energy. • A bouncing ball. • The running man.

  25. The SI unit for heat energy is the joule (pronounced “jool”). Another unit is the calorie. (exactly) 4.184 Joules = 1 calorie 4.184 J = 1 cal Units of Heat Energy This amount of heat energy will raise the temperature of 1 gram of water 1oC.

  26. Heat vs. Temperature A form of energy associated with small particles of matter. A measure of the intensity of heat, or of how hot or cold a system is. An Example of the Difference Between Heat and Temperature

  27. 100 g water 30oC 200 g water 30oC 8368 J 4184 J A B 100 g water 20oC 200 g water 20oC Twice as much heat energy is required to raise the temperature of 200 g of water 10oC as compared to 100 g of water. temperature rises 10oC heat beakers

  28. Specific Heat The specific heat of a substance is the quantity of heat required to change the temperature of 1 g of that substance by 1oC.

  29. The units of specific heat in joules are: Units of Specific Heat The units of specific heat in calories are:

  30. General Equation - Specific Heat ( ) specific heatof substance Δt = heat ( ) mass of substance The relation of mass, specific heat, temperature change (Δt), and quantity of heat lost or gained is expressed by the general equation:

  31. Calculate the specific heat of a solid in J/goC and in cal/ goC if 1638 J raise the temperature of 125 g of the solid from 25.0oC to 52.6oC. (mass of substance)(specific heat of substance)Δt = heat (g)(specific heat of substance)Δt = heat heat = 1638 J mass = 125 g Δt = 52.6oC – 25.0oC = 27.6oC

  32. Calculate the specific heat of a solid in J/goC and in cal/ goC if 1638 J raise the temperature of 125 g of the solid from 25.0oC to 52.6oC. Convert joules to calories using 1.000 cal/4.184 J

  33. A sample of a metal with a mass of 212 g is heated to 125.0oC and then dropped into 375 g of water at 240.0oC. If the final temperature of the water is 34.2oC, what is the specific heat of the metal? When the metal enters the water, it begins to cool, losing heat to the water. At the same time, the temperature of the water rises. This process continues until the temperature of the metal and the temperature of the water are equal, at which point (34.2oC) no net flow of heat occurs.

  34. A sample of a metal with a mass of 212 g is heated to 125.0oC and then dropped into 375 g of water at 240.0oC. If the final temperature of the water is 34.2oC, what is the specific heat of the metal? • Calculate the heat gained by the water. • Calculate the final temperature of the metal. • Calculate the specific heat of the metal.

  35. heat gained by the water = A sample of a metal with a mass of 212 g is heated to 125.0oC and then dropped into 375 g of water at 240.0oC. If the final temperature of the water is 34.2oC, what is the specific heat of the metal? Heat Gained by the Water temperature rise of the water Δt = 34.2oC – 24.0oC = 10.2oC

  36. heat lost by the metal heat gained by the water = = A sample of a metal with a mass of 212 g is heated to 125.0oC and then dropped into 375 g of water at 240.0oC. If the final temperature of the water is 34.2oC, what is the specific heat of the metal? Heat Lost by the Metal Once the metal is dropped into the water, its temperature will drop until it reaches the same temperature as the water (34.2oC). temperature drop of the metal Δt = 125.0oC – 34.2oC = 90.8oC

  37. The heat lost or gained by the system is given by: (mass) (specific heat) (Δt) = energy change specific heatof the metal = A sample of a metal with a mass of 212 g is heated to 125.0oC and then dropped into 375 g of water at 240.0oC. If the final temperature of the water is 34.2oC, what is the specific heat of the metal? rearrange

  38. Energy in Chemical Changes In all chemical changes, matter either absorbs or releases energy.

  39. Energy Release From Chemical Sources

  40. Chemical Changes Caused by Absorption of Energy

  41. Conservation of Energy An energy transformation occurswhenever a chemical change occurs. • If energy is absorbed during a chemical change, the products will have more chemical potential energy than the reactants. • If energy is given off in a chemical change, the products will have less chemical potential energy than the reactants.

  42. Conservation of Energy energy is absorbed higher potential energy energy is given off lower potential energy H2 + O2 have higher potential energy than H2O Burning of Hydrogen in Air Electrolysis of Water

  43. Law of Conservation of Energy Energy can be neither created nor destroyed, though it can be transformed from one form of energy to another form of energy.

  44. Concepts • Physical Properties • Distinguish Chemical from Physical Properties • Classify changes – Chemical or Physical • Kinetic vs. Potential Energy • Law of Conservation of Mass • Law of Conservation of Energy • Heat vs. Temperature • Use equation: (mass) (specific heat) (Δt) = heat

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