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* Energy: is the ability to do work or to produce change. Ex: lifting arm or melting snow. * SI expresses the unit of measure for energy in joules(J) * 1 J is the amount of energy needed to lift an object weighing 1 newton (N) to a height of 1 metre. Forms of Energy Thermal Energy: the energy that comes from the random motion of particles of a substance. Ex: melting snow, steam train, hot-air balloon Mechanical Energy: Results from the speed of an object, its mass and its relationship to its surroundings. Ex: a rock held at different heights, wind energy, hydraulic energy, creation of a crater.
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250 ml 50 º C 500 ml 50º C Both have the same temperature, but the second beaker contains twice the amount of thermal energy.
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FactorFactor variationResult Number of particlesMore particlesIncreased thermal energy Fewer particlesReduced thermal energy TemperatureHigher temperatureIncreased thermal energy Lower temperatureReduced thermal energy Properties affecting Thermal Energy
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* Radiant Energy: contained in and transported by electromagnetic waves. * Electromagnetic waves transport energy from one place to another. * Quantity depends on wavelength and amount of radiation. Shorter the wavelength the more energy transported. * Ex: light, UV rays in tanning, X- Ray images, radiation therapy * Chemical Energy: stored in the bonds of molecules. * Energy in reserve. Amount is dependant upon strength & number of bonds. Stronger bonds contain more energy. * Energy is released when the bonds are broken. Ex: burning a candle, combustion of gasoline in car, cellular respiration.
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* Transformation of Energy: is the changing of energy from one form to another. * Ex: burning a log: chemical energy stored in wood is transformed to radiant energy (light) and thermal energy (particle movement). * Energy transfer: is the movement of energy from one place to another. * Movement of energy from burning log to surroundings; heat. * Heat: transfer of thermal energy from one place to another. * Travels from place of higher temperature toward lower temperature. *Energy transfer and transformation can result in both chemical and physical changes.
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1. Changes of State 3 states of matter: solid, liquid and gas 3 states of matter: solid, liquid and gas The transformation from one state or phase to another. The transformation from one state or phase to another. H 2 O (s ) ↔ H 2 O (l) ( freezing ) (melting) Ex:
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CHANGES OF STATES/PHASE CHANGES 1) Melting/Fusion: Solid → Liquid Ex: Ice water 2)Freezing/Solidification: Liquid → Solid Ex. water Snow flakes 3)Vaporization (boiling & evaporation): Liquid → Gas Ex: water steam Phase changes: The change in thermal energy (addition or removal of heat) changes the forces of attraction causing the particles to move closer to, or further from, one another resulting in a change of state.
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4) Condensation: Gas → Liquid Ex: Steam water 5) Sublimation: Solid → Gas *The solid does not melt to liquid, Instead turns directly to gas. Ex. Dry Ice [CO 2 (s)] to CO 2 (g)] Deposition: 6) Deposition: Gas → Solid The gas cools but skips condensation and turns directly to a solid. Ex: Snow, frost, hail Ex: Iodine vapour -> Solid Iodine
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* The creation of a solution by a solute dissolved in a solvent. * Ex: sugar in water, carbon in iron. * Normally involves the absorption or release of energy. * When dissolution releases energy temperature * When dissolution absorbs energy temperature 3. Deformation Changing the shape of a material. Some are reversible (stretching a coil), some are permanent (tearing a sheet of metal). Involves an energy transfer, usually more than one. Ex: jumping on a trampoline (mechanical to elastic which is a reversible deformation)
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* Involves the production of one or more new substances. * One or more substances (reagents) react to make new substances (products) * Bonds between reagents change and reform making new substances. * Changes the nature and characteristic properties of matter. * Law of conservation of mass: all matter is transformed none is created or destroyed, # of atoms remains constant. Telling difference between chemical and physical changes: -The release of a gas-Greater changes of heat -Generation of light-Change of colour -Formation of a precipitate –Change in mass
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Chemical change: 2Na (s) + 2H 2 0 (l) → 2NaOH (aq) + H 2(g)
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Chemical Reactions can combine elements to make compounds (1. synthesis reaction) OR Chemical Reactions can break apart compounds into its elements (2. decomposition reaction)
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* The transformation of complex molecules into simpler molecules or into atoms. Is the opposite of synthesis. * Reaction where a compound separates into two or more compounds or elements. (AB = A + B) * The chemical energy of a molecule is released or transformed into other forms of energy. Ex: glycogen decomposing into glucose releases thermal energy, electrolysis of H 2 O uses energy The formation of a complex molecule from atoms or simpler molecules. Ex: H 2 reacts with O 2 to form H 2 O. Is a chemical reaction that either absorbs or releases energy. Reaction where 2 or more reactants combine to form a new product ( A + B = AB) Photosynthesis absorbs energy: 6CO 2 + 6 H 2 O + energy C 6 H 12 O 6 + 6O 2 Utilizes radiant energy to form stored energy as glucose. 2.Decomposition
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* Makes a new substance * Sign of a chemical change * Increase in mass * Ex. If you see mass, the ONLY thing you know is that a compound was made!!! + +
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* Two or more substances produced * Sign of a chemical change * Decrease in mass * Ex. If you see mass, the ONLY thing you know is that you started with a compound! + +
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* Is a chemical reaction involving oxygen in the air or a substance with similar properties to oxygen. Ex: iron rusting, banana ripening, fire, cellular respiration (opposite of photosynthesis). * 4 Fe + 3 O 2 2 Fe 2 O 3 +energy * Combustion is a form of oxidation that releases a large amount of energy. * Occurs when two solutions are combined and an insoluble or less soluble substance forms. Ex: when doing the Fehling reagent test for carbohydrates the presence of certain carbohydrates formed a precipitate. * Requires very little energy. 4. Precipitation
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