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Published byPeter Hancock Modified over 8 years ago
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Chapter 2 Matter and Energy
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Energy Energy—the capacity to do work Where does your energy come from? Can be in the forms: light, heat, chemical, mechanical, electrical, and sound
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Transfer of Heat Look at your food labels—bomb calorimeter Heat—energy transferred between objects that are at different temperatures Heat is transferred from a warmer to cooler objects
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Changes in Matter Physical Changes Melting Boiling Cutting Chemical Changes Cooking Baking Burning
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Change in Energy Evaporation—the changing from a liquid to a gas Energy must be put into the system to surpass the boiling point of a liquid. Energy may be released when going down the phase diagram, that is from vapor to liquid, etc.
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Endothermic and Exothermic Endothermic Heat is ABSORBED the system EX: melting of ice & boiling of water & cold packs Makes objects feel cooler! Exothermic Heat is RELEASED from the system EX: freezing of water & heat pack & glow sticks Makes objects feel hotter!
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Law of Conservation of Energy States that energy (E) cannot be created nor destroyed but can be changed from one form to another. The quantity of energy remains the same. E = mc 2
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Released as heat Worst industrial disaster: Grandcamp in Texas in April 1947. Cargo ship carrying fertilizer Kinetic E—the E of an object that is due to the object’s motion The object is moving!
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Temperature vs. Heat Temperature— actual measurement of the average kinetic E of the random motion of particles in a substance. A measure of how hot or cold something is. As kinetic E increases, so does the temperature! Heat is the E that is being transferred and temperature is the measurement!
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How to express temperature Kelvin (K): SI unit for temperature At 0K, absolute zero, all particles cease. K = o C + 273 Celsius ( o C): 0 o C is the freezing point of water 100 o C is the boiling point of water o C = K - 273
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Specific Heat The quantity of heat required to raise a unit of mass of homogeneous material 1K or 1 o C in a specified way.
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