the nature of energy u energy is the ability to do work or produce heat. u it exists in two basic...
TRANSCRIPT
![Page 1: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/1.jpg)
The Nature of Energy
![Page 2: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/2.jpg)
The Nature of Energy Energy is the ability to do work or
produce heat. It exists in two basic forms, potential
energy and kinetic energy.
![Page 3: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/3.jpg)
The Nature of Energy Kinetic energy is energy of motion. Kinetic energy increases as the
temperature of molecules goes up.
![Page 4: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/4.jpg)
The Nature of Energy Comparing any two samples, the one
with the higher temperature has the higher kinetic energy.
![Page 5: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/5.jpg)
The Nature of Energy Temperature is a measure of an
object’s average kinetic energy. The unit for temperature commonly
used by scientists is degrees Celsius or Kelvin.
![Page 6: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/6.jpg)
The Nature of Energy The potential energy of a substance
depends upon its composition: the type of atoms in the substance, the number and type of chemical bonds joining the atoms, and the particular way the atoms are arranged.
![Page 7: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/7.jpg)
The Nature of Energy
Chemical potential energy is stored in gasoline, wood, food, etc.
![Page 8: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/8.jpg)
Law of Conservation of Energy
The law of conservation of energy states that in any chemical reaction or physical process, energy can be converted from one form to another, but it is neither created nor destroyed.
![Page 9: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/9.jpg)
The Nature of Energy
Chemical systems contain both kinetic energy and potential energy.
Energy (kinetic and potential) of the particles of a substance changes when heated, cooled, or changing phase.
![Page 10: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/10.jpg)
The Nature of Energy
As you consider the phases - solid, liquid, gas – this is in order of increasing potential energy.
Solids have the least potential energy. Liquids have a moderate amount of potential energy. Gases will have the most potential energy.
![Page 11: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/11.jpg)
Heat
Heat, which is represented by the symbol q, is energy that is in the process of flowing from a warmer object to a cooler object.
The standard unit of heat and energy is the joule (J).
![Page 12: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/12.jpg)
Heat
Heat involves a transfer of energy between 2 objects due to a temperature difference.
![Page 13: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/13.jpg)
Heat flows Heat flows from “from “hot to hot to coldcold.”.”
![Page 14: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/14.jpg)
Law of Conservation of Energy
When the warmer object loses heat, its temperature decreases and q is negative.
When the cooler object absorbs heat, its temperature rises and q is positive.
![Page 15: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/15.jpg)
PHASE CHANGES
![Page 16: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/16.jpg)
Phase Changes
A material will change from one state or phase to another at specific combinations of temperature and surrounding pressure.
Typically, the pressure is atmospheric pressure, so temperature is the determining factor to the change in state in those cases.
![Page 17: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/17.jpg)
Liquid
Vaporization
Solid
Gas
????
????Condensation
![Page 18: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/18.jpg)
Condensation and Vaporization
![Page 19: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/19.jpg)
Vaporization
Vaporization is the process by which a liquid changes into a gas or vapor.
Vaporization is an endothermic process – the liquid absorbs heat.
![Page 20: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/20.jpg)
Evaporization
When vaporization occurs only at the surface of an uncontained liquid (no lid on the container), the process is called evaporation.
![Page 21: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/21.jpg)
Endothermic
Endothermic • Absorbs heat
• Would feel cold if you were to touch it
• Pulls in heat from its surroundings – such as your hand, and converts it to chemical potential energy
![Page 22: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/22.jpg)
Condensation is the process by which a gas or vapor becomes a liquid. It is the reverse of vaporization.
Condensation is exothermic – heat is released.
Condensation
![Page 23: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/23.jpg)
Endothermic
Exothermic • Releases heat
• Would feel hot if you were to touch it
• Release chemical potential energy and you would perceive it as heat
![Page 24: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/24.jpg)
Vaporization results in an increase in potential energy.
Condensation results in a decrease in potential energy.
Kinetic energy remains constant during vaporization and condensation.
Energy DuringVaporization & Condensation
![Page 25: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/25.jpg)
In a closed system, the rate of vaporization can equal the rate of condensation.
When the rates are equal the system is said to be in dynamic equilibrium.
Dynamic Equilibrium
![Page 26: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/26.jpg)
Molecules are constantly changing phase - “Dynamic”
The total amount of liquid and vapor remains constant - “Equilibrium”
Dynamic Equilibrium
![Page 27: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/27.jpg)
Vapor Pressure
Vapor pressure is the pressure exerted by a vapor over a liquid.
![Page 28: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/28.jpg)
Vapor Pressure
As temperature increases, water molecules gain kinetic energy and vapor pressure increases.
![Page 29: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/29.jpg)
Vapor Pressure
Vapor pressure does not change with surface area.
![Page 30: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/30.jpg)
Vapor Pressure
Vapor pressure for a liquid is lowered when sugar or salt is dissolved in the liquid.
![Page 31: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/31.jpg)
http://www.kentchemistry.com/links/Matter/VaporPressure.htm
Dynamic Equilibrium
![Page 32: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/32.jpg)
Boiling
When the vapor pressure of a liquid equals atmospheric pressure, the liquid has reached its boiling point, which is 100°C for water at sea level.
Standard atmospheric pressure equals 1 atm.
![Page 33: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/33.jpg)
Boiling
At this point, molecules throughout the liquid have the energy to enter the gas or vapor phase.
The temperature of a liquid can never rise above its boiling point.
![Page 34: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/34.jpg)
Liquid
Melting
Solid
Gas
????
????Freezing
![Page 35: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/35.jpg)
Melting and Freezing
![Page 36: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/36.jpg)
The melting of a solid occurs when the forces holding the particles together are broken and the solid becomes a liquid.
Melting is an endothermic process – the solid absorbs heat.
Melting
![Page 37: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/37.jpg)
Freezing occurs when a liquid becomes a crystalline solid.
Freezing is an exothermic process – the liquid releases heat.
The freezing point is the same as the melting point.
Freezing
![Page 38: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/38.jpg)
Melting results in an increase in potential energy.
Freezing results in a decrease in potential energy.
Kinetic energy remains constant during melting and freezing.
Energy DuringMelting & Freezing
![Page 39: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/39.jpg)
Liquid
Sublimation
Solid
Gas
????
????Deposition
![Page 40: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/40.jpg)
Sublimation and Deposition
![Page 41: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/41.jpg)
The process by which a solid changes directly into a gas without first becoming a liquid is called sublimation.
Solid air fresheners and dry ice are examples of solids that sublime.
Sublimation is endothermic.
Sublimation
![Page 42: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/42.jpg)
When a substance changes from a gas or vapor directly into a solid without first becoming a liquid, the process is called deposition.
Deposition is the reverse of sublimation.
Deposition
![Page 43: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/43.jpg)
Frost is an example of water deposition.
Deposition is exothermic.
Deposition
![Page 44: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/44.jpg)
Sublimation results in an increase in potential energy.
Deposition results in a decrease in potential energy.
Kinetic energy remains constant during sublimation and deposition.
Energy DuringSublimation & Deposition
![Page 45: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/45.jpg)
Phase Changes of Water and Energy
![Page 46: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/46.jpg)
Phase Changes of Water and Energy
![Page 47: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/47.jpg)
Solid Liquid Gas
Melting Vaporization
CondensationFreezing
Sublimation
Deposition
![Page 48: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/48.jpg)
Question
Classify the following phase change.
1. dry ice (solid carbon dioxide) to carbon dioxide gas
sublimation
![Page 49: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/49.jpg)
Question
Classify the following phase change.
2. ice to liquid water
melting
![Page 50: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/50.jpg)
Question
Classify the following phase change.
3. liquid water to ice
freezing
![Page 51: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/51.jpg)
Question
Classify the following phase change.
4. water vapor to liquid water
condensation
![Page 52: The Nature of Energy u Energy is the ability to do work or produce heat. u It exists in two basic forms, potential energy and kinetic energy](https://reader034.vdocuments.us/reader034/viewer/2022042702/56649d955503460f94a7d90f/html5/thumbnails/52.jpg)