Table of Contents Chapter: Heat and States of Matter Section 2: States of MatterStates of Matter Section 1: Temperature and Thermal Energy Section 3: Transferring Thermal EnergyTransferring Thermal Energy Section 4: Using Thermal EnergyUsing Thermal Energy

1 1 The motion of the particles in matter is described by kinetic theory of matter. Matter is composed of particles that are atoms, molecules, or ions that always are in random motion. Kinetic Theory of Matter Temperature and Thermal Energy

The temperature of a substance is a measure of the average kinetic energy of its particles. 1 1 The SI unit for temperature is the Kelvin (K). Temperature Temperature and Thermal Energy

1 1 Temperature Temperature and Thermal Energy Commonly used temperature scales are the Celsius scale and the Fahrenheit scale.

1 1 The sum of the kinetic and potential energies of all the particles in an object is the thermal energy of the object. The increase in an object’s speed doesn’t affect the random motion of its particles, so it doesn’t affect its thermal energy. Thermal Energy Temperature and Thermal Energy

1 1 Heat is thermal energy that flows from something at a higher temperature to something at a lower temperature. Heat is a form of energy, so it is measured in joules. Heat Temperature and Thermal Energy

1 1 The amount of thermal energy needed to raise the temperature of 1 kg of some material by 1°C is called the specific heat of the material. Specific heat is measured in joules per kilogram per degree Celsius. Specific Heat Temperature and Thermal Energy

1 1 Changes in Thermal Energy Temperature and Thermal Energy

1 1 The specific heat of a material can be measured using a device called a calorimeter. In a calorimeter, a heated sample transfers thermal energy to a known mass of water. Measuring Specific Heat Temperature and Thermal Energy

1 1 Measuring Specific Heat Temperature and Thermal Energy The thermal energy released by the sample is equal to the thermal energy absorbed by the water.

1 1 Section Check Question 1 How is temperature related to kinetic energy? FL: SC.B.1.4.3

1 1 Section Check Temperature is a measure of the average kinetic energy of the particles in an object or material. As the temperature increases, the average speed of the particles increases. Answer FL: SC.B.1.4.3

1 1 Section Check Question 2 How does thermal energy differ from kinetic energy? Answer Thermal energy is the sum of the kinetic and potential energy of all the particles in an object. FL: SC.B.1.4.3

1 1 Section Check Question 3 The amount of heat that is needed to raise the temperature of 1 kg of a material by 1º C is called the __________ of the material. A. density B. mass C. specific heat D. thermal energy

1 1 Section Check Answer The answer is C. Specific heat is measured in joules/kilogram °C.

2 2 States of Matter The particles of a solid are packed closely together and are constantly vibrating in place. Four States of Matter The attractions between particles are strong and solids have a fixed volume and shape. Solid State

2 2 States of Matter The attractive forces are strong enough to cause particles to cling together. Liquid State Liquids have a definite volume, but not a definite shape.

2 2 States of Matter In a gas the forces between particles are so weak that the particles no longer cling together. Gas State Gases do not have a definite shape or volume.

2 2 States of Matter The most common state of matter in the universe is the plasma state. Plasma State Plasma is matter consisting of positively and negatively charged particles and does not have a definite shape or volume.

2 2 States of Matter The temperature at which a solid begins to melt is its melting point. Changing States The amount of energy required to change 1 kg of a substance from a solid to a liquid at its melting point is known as the heat of fusion. Melting

2 2 States of Matter The heat of fusion is also the energy released when a liquid freezes. Freezing The attractive forces are strong enough that the particles form an ordered arrangement.

2 2 States of Matter Vaporization occurs as liquid changes into a gas. Vaporization Vaporization that occurs at the surface of a liquid is called evaporation. Evaporation causes the temperature of the liquid to decrease.

2 2 States of Matter The boiling point of a liquid is the temperature at which the pressure of the vapor in the liquid is equal to the external pressure acting on its surface. Boiling The heat of vaporization is the amount of energy required for 1 kg of the liquid at its boiling point to become a gas.

2 2 States of Matter The heat of vaporization is also the amount of energy released during condensation. Condensation This graph shows the temperature change of water as thermal energy is added.

2 2 States of Matter The average kinetic energy of the water molecules doesn’t change. Condensation The temperature remains constant during melting.

2 2 States of Matter Condensation of the gas increases as energy is added. After the liquid water has changed completely into a gas, the temperature

2 2 States of Matter The increased separation between the particles results in the expansion of the object and the size of the object increases. Thermal Expansion When a material cools, the particles in the material move more slowly and become closer together. The Thermal Expansion of Matter

2 2 States of Matter The forces between the particles in liquids are weaker than the forces between the particles in a solid. Thermal Expansion of Liquids The same temperature increase usually causes liquids to expand much more than solids.

2 2 States of Matter In a gas, the forces between particles are much weaker than they are in liquids. Thermal Expansion of Gases Gases expand even more than liquids for the same increase in temperature.

2 2 Section Check Question 1 _________ is a state of matter consisting of positively and negatively charged particles that exists where the temperature is extremely high. FL: SC.A A. Gas B. Liquid C. Plasma D. Solid

2 2 Section Check Answer The answer is C. Plasma is found in the Sun, stars, lightning bolts and neon lights. FL: SC.A.1.4.3

2 2 Section Check Question 2 Most __________ materials have a specific type of geometric arrangement. FL: SC.A A. gaseous B. inert C. liquid D. solid

2 2 Section Check The answer is D. The particles in most solids align themselves in ordered geometric patterns. Answer FL: SC.A.1.4.3

2 2 Section Check Question 3 The amount of energy required to change 1 kg of a substance from a solid to a liquid at its melting point is known as the _______. A. heat of energy B. heat of fusion C. heat of melting D. heat of vaporization

2 2 Section Check Answer The correct answer is B. Heat of fusion causes an ice cube to become liquid water.

3 3 Ways to Transfer Thermal Energy This transfer of thermal energy between colliding particles is conduction. Transferring Thermal Energy Kinetic energy is transferred when these faster-moving atoms collide with slower- moving particles. Conduction

3 3 Thermal Conductors The rate at which thermal energy is transferred depends on the material. Transferring Thermal Energy A material in which thermal energy is transferred easily is called a thermal conductor. Gases are poorer thermal conductors than solids or liquids.

3 3 Convection Convection is the transfer of thermal energy in a fluid by the movement of fluid from place to place. Transferring Thermal Energy A fluid expands as its temperature increases. The density of the fluid therefore decreases.

3 3 Convection The warmer water is less dense and is forced upward by the sinking cooler water. Transferring Thermal Energy The warm water transfers thermal energy to the cooler water around it.

3 3 Convection Transferring Thermal Energy When the warm water cools, it becomes denser than the surrounding water and sinks. The rising and sinking water forms a convection current.

3 3 Radiation Radiation is the transfer of energy by electromagnetic waves. Transferring Thermal Energy Radiation can pass through solids, liquids, and gases, but the transfer of energy by radiation is most important in gases.

3 3 Radiation Transferring Thermal Energy When radiation strikes a material, some energy is absorbed, some is reflected, and some may be transmitted through the material.

3 3 Thermal Insulators Transferring Thermal Energy A material in which thermal energy moves slowly is a thermal insulator. Materials that are good conductors of thermal energy, such as metals are poor thermal insulator.

3 3 Section Check Question 1 Describe the difference between conduction and convection.

3 3 Section Check Conduction transfers thermal energy without transferring matter. In convection, the more energetic particles move from one place to another. Answer Convection currents result when heated fluid rises and cooler fluid sinks.

3 3 Section Check Question 2 __________ is the transfer of energy by electromagnetic waves. Answer The transfer of energy by electromagnetic waves is radiation. Radiation is how Earth gets heat from the Sun.

3 3 Section Check Question 3 Which of the following is the least effective insulator? FL: SC.A A. air B. fiberglass C. metal D. wood

3 3 Section Check Answer The answer is C. Metals are good conductors of heat. And heat flows more rapidly in them. FL: SC.A.1.4.2

4 4 How is thermal energy used? Fuel is burned in a furnace and heats a volume of air. A fan blows the heated air through a series of large pipes called ducts. Using Thermal Energy Heating Systems Forced-Air Systems The ducts lead to openings called vents in each room.

4 4 Radiator Systems A radiator is a closed metal container that contains hot water or steam. The thermal energy contained in the hot water or steam is transferred to the air surrounding the radiator by conduction. Using Thermal Energy

4 4 Electric Heating Systems In an electric heating system, electrically heated coils placed in floors and in walls heat the surrounding air by conduction and convection. Using Thermal Energy

4 4 Thermodynamics A system is anything you can draw a boundary around. Using Thermal Energy Heating and Work Increase Thermal Energy The energy transferred to a system is the amount of energy flowing into the system across the boundary. The work done on a system is the work done by something outside the system’s boundary.

4 4 The First Law of Thermodynamics According to the first law of thermodynamics, the increase in thermal energy of a system equals the work done on the system plus the thermal energy transferred to the system. Using Thermal Energy The increase in energy of a system equals the energy added to the system.

4 4 Closed and Open Systems A system is an open system if thermal energy flows across the boundary or if work is done across the boundary. Using Thermal Energy If no thermal energy flows across the boundary and no outside work is done, the system is a closed system.

4 4 The Second Law of Thermodynamics The second law of thermodynamics states it is impossible for thermal energy to flow from a cool object to a warmer object unless work is done. Using Thermal Energy

4 4 Converting Thermal Energy to Work No device or process can convert thermal energy completely into work. Using Thermal Energy

4 4 Heat Engines A device that converts thermal energy into work is called a heat engine. Using Thermal Energy When thermal energy is converted into work, some thermal energy always is transferred to the surroundings.

4 4 Internal Combustion Engines The heat engine in a car is an internal combustion engine. Using Thermal Energy Each cylinder contains a piston that moves up and down. Each up or down movement of the piston is called a stroke.

4 4 Internal Combustion Engines Using Thermal Energy

4 4 Moving Thermal Energy Liquid coolant is pumped through an expansion valve and changes into a gas. Using Thermal Energy The cold gas is pumped through pipes inside the refrigerator. The coolant absorbs thermal energy and the inside of the refrigerator cools.

4 4 Entropy According to the laws of thermodynamics, work can be converted completely into thermal energy, but thermal energy cannot be converted completely into work. Using Thermal Energy Entropy is a measure of how spread out, or dispersed, energy is. Entropy increases when energy becomes more spread out and less concentrated.

4 4 Entropy Always Increases According to the entropy principle, all events that occur cause the entropy of the universe to increase. Using Thermal Energy The energy that becomes spread out is no longer useable.

4 4 Section Check Question 1 The study of the relationship among thermal energy, heat and work is __________. FL: SC.B A. electrical engineering B. graphical analysis C. specific heat D. thermodynamics

4 4 Section Check Answer The answer is D, thermodynamics. FL: SC.B.1.4.6

4 4 Section Check Question 2 According to __________, the increase in thermal energy of a system equals the work done on the system plus the heat transferred to the system. FL: SC.B A. Newton’s First Law B. Newton’s Second Law C. the first law of thermodynamics D. the second law of thermodynamics

4 4 Section Check The answer is C. Doing work on a system is a way of adding energy to a system. Answer FL: SC.B.1.4.6

4 4 Section Check Question 3 How does a refrigerator work? Answer The refrigerator coolant absorbs thermal energy from inside the refrigerator and releases it into the surrounding air.

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