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Chapter 2 Energy & Matter

Chapter 2 Energy & Matter. Energy – the capacity to do work or produce heat Examples of energy: moving car, sunlight, food, oil 3 categories of energy: Radiant – all forms of light Kinetic energy – movement energy Potential energy – stored energy Gravitational energy – energy of position

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Chapter 2 Energy & Matter

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  1. Chapter 2 Energy & Matter • Energy – the capacity to do work or produce heat • Examples of energy: moving car, sunlight, food, oil • 3 categories of energy: • Radiant – all forms of light • Kinetic energy – movement energy • Potential energy – stored energy Gravitational energy – energy of position Electrical energy Chemical energy

  2. Measuring energy 1 calorie (cal) – amount of heat to raise 1 gram of water 1 Co 1 food calorie (Cal) = 1000 cal = 1 kcal Chocolate bar is about 200 Cal (200 kcal) SI unit of heat is the joule (J) 1 cal = 4.184 J

  3. Law of Conservation of energy • Energy cannot be created or destroyed but can be changed from one form to another. Energy transformation Energy is not lost but changes forms. Gravitational potential Kinetic Kinetic Food chemical potential Heat and sound as arrow strikes the ground

  4. Temperature (3 temp. scales)Fahrenheit, Celsius, Kelvin

  5. Develop equations to convert F to C and C to F T 180 Fo = 100 Co 9 Fo F = C + 32 oF 5 Co 5 Co C = (F – 32 Fo) 9 Fo

  6. Kelvin temp scale – there are no negative temperatures • The coldest temperature is 0 K which is -273 oC oK = oC + 273 (see page 64 “Pursuing Absolute Zero”) • If matter reached absolute zero, all motion would stop • The closer any thing gets to absolute zero the harder it is to remove any more heat. • It is a natural limit in nature (like the speed of light)

  7. Matter • Anything that has mass and occupies volume • States of Matter • Solid – holds a particular shape and has definite volume • Liquid – no particular shape but has definite volume • Gas – no definite shape or volume, fills all available space • Plasma – like gas only exists at high temps (millions of degrees) • On the sun and in a lightning bolt HEATING

  8. Changes in state – by heating and cooling • Properties of matter – anything that can be used to describe matter • Physical properties – properties that can be determined without a chemical reaction • Chemical properties – properties that can only be determined by a chemical reaction • Physical change – no new substance produced • Chemical change – new substance produced (something that was not there before) • Law of Conservation of Matter – matter cannot be created or destroyed

  9. Elements and Compounds • Element – a substance that cannot be separated into simpler substances by a chemical change • - Is listed on the Periodic Chart • Compound – two or more elements combined • Antwan Lavoisier (luhv-wahz-ee-ay) – father of modern chemistry, careful experiments and precise measurements Na H2O Sc SC O2 O3 Element Compound Element Compound Element Element

  10. Mixture – two or more substances stirred together but not chemically combined • Heterogeneous mixture – contains visibly different parts (even very small particles) • Homogeneous mixture – the same throughout Separating Mixtures • Can be separated by physical means; filtration, crystallization, distillation, chromatography

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