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Energy and Reactions

Energy and Reactions. matter and energy. matter: anything that has mass and takes up space energy: ability to do work or cause change energy is used anytime a change in matter occurs. Nature of Energy. Energy is all around you! You can hear energy as sound. You can see energy as light.

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Energy and Reactions

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  1. Energy and Reactions

  2. matter and energy • matter: anything that has mass and takes up space • energy: ability to do work or cause change • energy is used anytime a change in matter occurs

  3. Nature of Energy • Energy is all around you! • You can hear energy as sound. • You can see energy as light. • And you can feel it as wind.

  4. Nature of Energy • You use energy when you: • hit a softball. • lift your book bag. • compress a spring.

  5. Nature of Energy Living organisms need energy for growth and movement.

  6. Nature of Energy • Energy is involved when: • a bird flies. • a bomb explodes. • rain falls from the sky. • electricity flows in a wire.

  7. energy Energy is the ability or the potential to make something happen (do work); that is to move or to change a condition • many forms • mechanical • thermal • electromagnetic • electrical • chemical

  8. Heat Energy • The internal motion of the atoms is called heat energy, because moving particles produce heat. • Heat energy can be produced by friction. • Heat energy causes changes in temperature and phase of any form of matter.

  9. Chemical Energy • Chemical Energy is required to bond atoms together. • And when bonds are broken, energy is released.

  10. Chemical Energy • Fuel and food are forms of stored chemical energy.

  11. Electromagnetic Energy • Light is a form of electromagnetic energy. • Each color of light (Roy G Bv) represents a different amount of electromagnetic energy. • Electromagnetic Energy is also carried by X-rays, radio waves, and laser light.

  12. Energy Conversion • Energy can be changed from one form to another. Changes in the form of energy are called energy conversions.

  13. Energy conversions • All forms of energy can be converted into other forms. • The sun’s energy through solar cells can be converted directly into electricity. • Green plants convert the sun’s energy (electromagnetic) into starches and sugars (chemical energy).

  14. changes in matter Energy is used anytime a change in matter occurs • two kinds changes in matter • physical changes • chemical changes

  15. physical change • alters form or appearance of material, but does not change material into brand new substance • examples • chopping wood • bending wire • molding clay

  16. chemical change • produces new substances • examples • wood burning • sour milk

  17. Chemical Reactions • Chemical reactions occur when bonds between the outermost (valence) electrons are formed or broken

  18. Chemical Reactions • Chemical reactions involve changes in matter, the making of new materials with new properties, and energy changes.

  19. The charcoal used in a grill is basically carbon. The carbon reacts with oxygen to yield carbon dioxide. The chemical equation for this reaction, C + O2 CO2, contains the same information as a sentence but has quantitative meaning as well.

  20. Chemical Reaction Equations H2 + Cl2   -->   2 HCl • Symbols represent elements, formulas describe compounds, chemical equations describe a chemical reaction

  21. Chemical Reaction Equations H2 + Cl2   -->   2 HCl

  22. Chemical ReactionEquations • Chemical equations show what enters the reaction - reactants (the molecules shown on the left of the arrow) and what comes out of the reaction - products (the molecules shown on the right of the arrow).

  23. Chemical Reaction Equations H2 + Cl2   -->   2 HCl reactants  -->   products

  24. Subscripts vs. Coefficients The subscripts tell you how many atoms of a particular element are in a compound. The coefficient tells you about the quantity, or number, of molecules of the compound.

  25. Chemical Equations 4 Al + 3 O2 ---> 2 Al2O3 This equation means 4 Al atoms + 3 O2 molecules ---produces---> 2 molecules of Al2O3

  26. Endergonic & Exergonic reactions Exergonic Energy OUT Breaking bonds apart Endergonic Energy IN Putting together bonds

  27. Endergonic or Exergonic reactions? What types of energy?

  28. Endergonic & Exergonic reactions vs. Endothermic & Exothermic reactions Therm – heat Ergon – any type of energy so Endothermic reaction is a type of endergonic reaction

  29. Endergonic reaction – any type of energy taken in Endothermic reaction – only heat energy taken in Exergonic reaction – any type of energy given off Exothermic reaction – only heat energy given off

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