Chapter 4
- 1. Properties of Matter Chapter 4
- 2. Chapter Outline 4.1 Properties of Substances 4.2 Physical Changes 4.3 Chemical Changes 4.4 Conservation of Mass 4.5 Energy 4.6 Heat: Quantitative Measurement 4.7 Energy in Chemical Changes 4.8 Conservation of Energy
- 4. 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. Properties of a Substance
- 6. The inherent characteristics of a substance that are determined without changing its composition. Examples: taste color physical state melting point boiling point
- 7. 2.4 times heavier than air color is yellowish-green odor is disagreeable melting point –101 o C boiling point –34.6 o C Physical Properties of Chlorine
- 9. Describe the ability of a substance to form new substances, either by reaction with other substances or by decomposition.
- 10. 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. Chemical Properties of Chlorine
- 12. Physical Changes
- 13. Changes in physical properties (such as size shape and density) or changes in the state of matter without an accompanying change in composition. Examples: Physical Changes tearing of paper change of ice into water change of water into steam heating platinum wire No new substances are formed.
- 14. Chemical Changes
- 15. In a chemical change new substances are formed that have different properties and composition from the original material.
- 16. 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 and 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.
- 17. Formation of Copper(II) Oxide Copper(II) oxide is made up of Cu 2+ and O 2- Neither Cu nor O 2 contains Cu 2+ or O 2- A chemical change has occurred. 4.2
- 18. Water is decomposed into hydrogen and oxygen by passing electricity through it. 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. They are both colorless gases. But the burning splint is extinguished when placed into the water sample.
- 20. Water decomposes into hydrogen and oxygen when electrolyzed. reactant products yields
- 21. Chemical symbols can be used to express chemical reactions
- 22. Water decomposes into hydrogen and oxygen when electrolyzed. reactant yields 2H 2 O 2H 2 O 2 products
- 23. Copper plus oxygen yields copper(II) oxide. yield product reactants heat
- 24. Copper plus oxygen yields copper(II) oxide. heat yield product reactants 2Cu O 2 2Cu 2 O
- 26. Conservation of Mass
- 27. No change is observed in the total mass of the substances involved in a chemical change.
- 28. sodium + sulfur sodium sulfide 78.1 g 78.1 g product mass products 78.1 g reactant -> 46.0 g 32.1 g mass reactants =
- 29. Energy
- 30. Energy is the capacity to do work
- 31. Types of Energy mechanical chemical electrical heat nuclear radiant
- 32. Potential Energy Energy that an object possesses due to its relative position.
- 33. The potential energy of the ball increases with increasing height. increasing potential energy 50 ft 20 ft increasing potential energy
- 34. Potential Energy Stored energy.
- 35. 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.
- 36. Kinetic Energy Energy matter possesses due to its motion.
- 37. Moving bodies possess kinetic energy . The flag waving in the wind.
- 38. Moving bodies possess kinetic energy. A bouncing ball. The running man.
- 39. The runner Moving bodies possess kinetic energy.
- 40. The soccer player. Moving bodies possess kinetic energy.
- 41. Heat: Quantitative Measurement
- 42. Heat A form of energy associated with small particles of matter. Temperature A measure of the intensity of heat, or of how hot or cold a system is.
- 43. Units of Heat Energy
- 44. The SI unit for heat energy is the joule (pronounced “jool”). Another unit is the calorie. This amount of heat energy will raise the temperature of 1 gram of water 1 o C. 4.184 J = 1 cal (exactly) 4.184 Joules = 1 calorie
- 45. An Example of the Difference Between Heat and 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.
- 46. Twice as much heat energy is required to raise the temperature of 200 g of water 10 o C as compared to 100 g of water. 200 g water 20 o C A 100 g water 20 o C B heat beakers temperature rises 10 o C 100 g water 30 o C 200 g water 30 o C 4184 J 8368 J
- 47. Specific Heat
- 48. The specific heat of a substance is the quantity of heat required to change the temperature of 1 g of that substance by 1 o C.
- 50. The units of specific heat in joules are :
- 51. The units of specific heat in calories are :
- 52. The relation of mass, specific heat, temperature change ( Δ t ), and quantity of heat lost or gained is expressed by the general equation: Δ t = heat mass of substance ) ( specific heat of substance ) (
- 53. Example 1
- 54. Calculate the specific heat of a solid in J/g o C and in cal/ g o C if 1638 J raise the temperature of 125 g of the solid from 25.0 o C to 52.6 o C. (mass of substance)(specific heat of substance) Δ t = heat (g)(specific heat of substance) Δ t = heat heat = 1638 J mass = 125 g Δ t = 52.6 o C – 25.0 o C = 27.6 o C
- 55. Calculate the specific heat of a solid in J/g o C and in cal/ g o C if 1638 J raise the temperature of 125 g of the solid from 25.0 o C to 52.6 o C. Convert joules to calories using 1.000 cal/4.184 J
- 56. Energy in Chemical Changes
- 57. In all chemical changes, matter either absorbs or releases energy .
- 58. Energy Release From Chemical Sources Chemical changes occurring within body cells. Body Combustion of fuels. Heat and Light A lightstick. Fuel combustion. Light Storage batteries Electrical Energy Source Type of Energy
- 59. Chemical Changes Caused by Absorption of Energy Photosynthesis in green plants. Light Electroplating of metals. Decomposition of water into hydrogen and oxygen Electrical Chemical Change Type of Energy
- 61. An energy transformation occurs whenever 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.
- 62. 4.4 H 2 + O 2 have higher potential energy than H 2 O Electrolysis of Water Burning of Hydrogen in Air energy is given off energy is absorbed higher potential energy lower potential energy
- 63. Law of Conservation of Energy Energy cannot be created or destroyed, it can only change forms.
- 64. The End