The Human Organism and the Power of Energy Chapter 2 The Human Organism and the Power of Energy

Energy Types and Transformations Lesson 2.1 Energy Types and Transformations

ENERGY ENERGY is the capacity to do work or cause a change There are many forms of energy Some forms of energy are listed on the next slide All forms of energy can be measured in JOULES The main unit of energy is the Joule (J). A Joule is the amount of energy it takes to lift a Newton (about 100g) one metre. 1000 Joules = 1 kilojoule (kJ)

These are the 4 energy forms that we will study in more detail. Some Forms of Energy Energy Form Energy source or example Solar Energy Energy from the sun or sunlight, eg. Solar panel Elastic Energy Energy from springs or elastics, eg. Watchsprings Electrical Energy Energy generated by electrical stations or batteries Wind Energy Energy from moving air, eg. Windmill Sound Energy Energy from sound, eg. Stereo speakers Hydraulic Energy Energy from moving water, eg. Waterfall or dam Thermal Energy Energy from hot, fast-moving molecules, eg. fire Radiant Energy Energy from electromagnetic radiation, eg. Light, heat Chemical Energy Energy from chemical bonds, eg. Food energy, Mechanical Energy Energy from moving objects, eg. Vehicles. These are the 4 energy forms that we will study in more detail.

As you can see, even in solids, the molecules vibrate a bit THERMAL ENERGY Thermal energy comes from the random motion of the particles (Temperature of molecules) that make up a substance and the amount of particles (mass). The faster the molecules of a substance move, the hotter the substance seems to us. Really fast molecules can even make flames! Cold Warm Hot As you can see, even in solids, the molecules vibrate a bit

RADIANT ENERGY Radiant Energy is contained in, and transported by electromagnetic waves Light is the most obvious form of radiant energy The shorter the wavelength the greater the energy Other forms of radiant energy include: X-Rays Radio Waves Ultraviolet Rays Infra-red Radiation (radiated heat) Gamma rays, cosmic rays (powerful radiation)

CHEMICAL ENERGY CHEMICAL ENERGY is stored in the bonds of molecule or by forming bonds. Like the energy in gasoline, or wood that you burn, or any other form of fossil fuel. Also, the energy used by life, such as the energy in food, is chemical energy.

MECHANICAL ENERGY MECHANICAL ENERGY results from the speed and mass of an object, and from its relationship to its surroundings. In other words, mechanical energy comes from the movement of objects. Falling objects, moving vehicles, mechanical devices and spinning wheels all have mechanical energy.

ENERGY TRANSFORMATION ENERGY TRANSFORMATION is changing energy from one form to another Examples: Radiant  to  Thermal (sun warms ground) Chemical  Radiant  Thermal (burning causes light & heat) Radiant  to  Chemical (photosynthesis) Heat (thermal energy) Radiant Radiant (light) Flame (radiant energy) Food (chemical) Log (chemical energy) Thermal (heat)

Assignments on Energy Types and Transformations Textbook pp. Workbook pp.23 to 26

How energy causes changes in matter Lesson 2.2 How energy causes changes in matter

Changes and Energy Energy can cause changes in matter, and changes in matter can produce energy.

Types of Changes: Two Types of Changes Physical Change Chemical Change

Physical Change: Does not change the chemical composition of a substance. It does not affect the nature or characteristic properties of the substance. Process is sometimes* reversible for changes of state Ex. Crumpling & smoothing out paper Ex. Freezing water and thawing ice Ex. Sublimation – from solid to gas (ex. dry ice (CO2) or iodine) *there are a few physical changes that are difficult to reverse.

Physical Change Key Words: Crush/PulverizePhysical change Tells you a physical change occurred Physical Change Key Words: Crush/PulverizePhysical change Melt (Fusion)Physical change Evaporation Physical change Condensation Physical change Sublimation Physical change Solidification Physical change Dissolve Physical change

Energy and Change of State (some people say “Phase” instead of “State”) Adding thermal energy to an object makes its particles (ie. Atoms or Molecules) move faster. If the particles move fast enough, the substance may change state, going from solid to liquid or from liquid to gas. Change of state is a PHYSICAL change caused by changing the amount of thermal energy in a substance

Physical Changes of State Absorbs Energy GAS Releases Energy They just move faster (or slower) DEPOSITION (solid sublimation) SUBLIMATION (gaseous) When a substance changes state it is always a physical change! Its molecules don’t change VAPORIZATION (evaporation) CONDENSATION (liquid) FUSION (Melting) SOLID LIQUID SOLIDIFICATION(Freezing)

Chemical Changes: Changes the chemical composition or make-up of the substance New substances are formed with new properties Not easily reversible (Reversible only through chemical means or reactions) Rust

Signs of Chemical Changes: Tells you a chemical change occurred Signs of Chemical Changes: Formation of a new gas when two substances mix. Formation of a precipitate from mixing two solutions. A significant change in colour when materials react. Release of heat &/or light when materials are mixed Increase or decrease in mass

Be Careful! Pay attention to the “when” part of each clue. Eg. “It is a chemical reaction if gas is released when two materials mix” One of these is definitely a chemical change, the others are not: 1) Gas bubbles are released when a pop bottle is opened 2) Gas bubbles are released when vinegar and baking soda mix. 3) Gas bubbles are released when water boils. #2 is the chemical change. #1 is not, since the release of gas is due to pressure change. #3 is not, since it is a change of state (liquid to gas)

Be Careful! Pay attention to the “when” part of each clue. “It is a chemical reaction if a significant change in colour occurs when materials react.” One of these is definitely a chemical change, the others may not be: 1) Base added to phenolphthalein changes it from clear to bright purple-pink. 2) Wet blue jeans look darker than dry ones. 3) Mixing yellow and blue paint makes green paint. #1 is the chemical change. #2 is not, since the colour change is not significant. #3 is not, since it is a simple blending of existing colours, not a reaction.

Chemical Change: Synthesis The formation of a complex molecule out of atoms or simpler molecules. Reactants Products Synthesis H H H H O O H H O O H H become O2 + 2 H2 Three simple molecules 2 H2O Two more complex molecules

Chemical Change: Decomposition When complex molecules are transformed into simpler molecules or atoms Al Al O O O O O O Al Al O O Al Al O O Al Al O O Become... 4 Al + 3 O2 Seven simpler molecules or atoms 2 Al2O3 two complex molecules

Chemical Change: Oxidation When oxygen combines with a material to change it. rusting of iron or corrosion of any metal is an example of slow oxidation. Combustion or burning is an example of rapid oxidation. Note: This type of oxidation is also a synthesis. Some oxidations may be decomposition. 4 Fe + 3O2  2Fe2O3 C + O2  CO2 Fuel

Chemical Change: Precipitation In chemistry, precipitation is the formation of a solid that is insoluble following the mixing of two solutions In other words, if you mix two transparent solutions and produce a cloudy mixture that eventually settles to form a powdery solid, that is a chemical precipitation. Don’t mix up chemical precipitation with meteorological precipitation, which is rain or snow. Transparent Cloudy Transparent

Examples: Physical Change Sublimation Freezing Condensation Evaporation Pulverization (crush) Solidification Dissolving Chemical Change - Burning - Neutralization - Combustion Oxidation Synthesis Decomposition Precipitation

Ex #1: Which of the following are examples of physical changes? 1. Melting Butter 4. Crushing Rock 2. Rusted Car 5. Condensation 3. Dissolving Sugar in Tea 6. Burning Wood

Ex #2: Which of the following are examples of chemical changes? 1. Cooking an egg 4. Freezing Rain 2. Rotting food 5. Burning a candle 3. Sublimation of Dry Ice 6. Crumpling Paper

Ex #3: Chemical Change Physical Change Where did a chemical change occur? A physical change? You carry out the following steps of an experiment & record your observations. Ex #3: 1. You place a powder in a test tube 2. You heat the test tube. You notice that a colorless gas & a copper-colored liquid are produced. 3. You collect the copper-colored liquid & cool it. It becomes a solid. Chemical Change Physical Change

Assignments on Physical and Chemical Changes Read Textbook pp. 43 to 58, q. 9-15 Do Workbook pp. 23-26 (energy) Do Workbook pp. 27-36 (changes)

Chapter End Questions Textbook pages 59 to 61 Write down the date of the chapter 2 test in your agenda or homework book.