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Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
Chemical reactions and thermodynamics
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Chemical reactions and thermodynamics

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  • 1. CHEMICAL REACTIONS AND THE LAW OF THERMODYNAMICS
  • 2. A review of energy <ul><li>energy comes in many forms </li></ul><ul><ul><li>thermal </li></ul></ul><ul><ul><li>nuclear </li></ul></ul><ul><ul><li>mechanical (including kinetic and potential) </li></ul></ul><ul><ul><li>electromagnetic </li></ul></ul><ul><ul><li>chemical </li></ul></ul><ul><li>Living organisms use chemical energy to perform life functions such as active transport and mitosis </li></ul><ul><ul><li>energy changes form but is never completely lost </li></ul></ul>
  • 3. Two types of chemical reactions <ul><li>Exergonic </li></ul><ul><ul><li>a chemical reaction that releases energy by breaking bonds between molecules </li></ul></ul><ul><ul><li>occur spontaneously most of the time (sometimes requires a small amount of energy to get started) </li></ul></ul><ul><ul><li>example: breaking down food molecules during digestion </li></ul></ul><ul><ul><li>often these types of reactions produce heat </li></ul></ul>
  • 4. Two types of chemical reactions <ul><li>Endergonic reactions </li></ul><ul><ul><li>bonds between molecules are formed </li></ul></ul><ul><ul><li>requires a good amount of energy to happen </li></ul></ul><ul><ul><ul><li>this energy is called activation energy </li></ul></ul></ul><ul><ul><li>often absorbs heat when reaction occurs </li></ul></ul><ul><ul><li>do not occur spontaneously, but only when energy is available </li></ul></ul><ul><ul><li>many cellular reactions are endergonic, therefore cells must have a way to store the needed energy for use in chemical reactions. </li></ul></ul><ul><ul><li>source of info: http://library.thinkquest.org/27819/ch4_2.shtml </li></ul></ul>
  • 5. Theories versus Laws <ul><li>Theory </li></ul><ul><ul><li>Explanation of a set of related observations or events based upon proven hypotheses. </li></ul></ul><ul><ul><ul><li>More like a scientific law than a hypothesis . </li></ul></ul></ul><ul><ul><li>Verified multiple times by detached groups of researchers. </li></ul></ul><ul><ul><li>One scientist cannot create a theory, he/she can only create a hypothesis. </li></ul></ul><ul><ul><ul><li>Examples : The theory of evolution, the theory of relativity, and the quantum theory . </li></ul></ul></ul>
  • 6. Theories versus Laws <ul><li>Law </li></ul><ul><li>A statement of fact meant to explain , in concise terms, an action or set of actions. </li></ul><ul><li>Generally accepted to be true and universal by all of the scientific community </li></ul><ul><li>Can sometimes be expressed in terms of a single mathematical equation. </li></ul><ul><li>They are accepted at face value based upon the fact that they have always been observed to be true. </li></ul><ul><ul><li>Examples : The law of gravity, Newton’s laws of motion, the laws of thermodynamics . </li></ul></ul>
  • 7. The laws of thermodynamics <ul><li>Thermodynamics is the study of energy </li></ul><ul><li>First law (law of conservation of energy) </li></ul><ul><ul><li>states that energy is always conserved </li></ul></ul><ul><ul><ul><li>it is not created or destroyed </li></ul></ul></ul><ul><ul><ul><li>it simply changes from one form to another </li></ul></ul></ul><ul><ul><li>Example: the potential energy stored in a stretched rubber band turns into kinetic energy (energy of motion) when the rubber band snaps </li></ul></ul><ul><ul><ul><li>total amount of energy stays the same </li></ul></ul></ul><ul><ul><li>In short, the quantity of energy always stays the same </li></ul></ul>
  • 8. The laws of thermodynamics <ul><li>Second law (law of entropy) </li></ul><ul><ul><li>states that even though the total amount of energy does not change in a system, the form of energy will increasingly go from usable (like chemical energy) to unusable forms (like heat). </li></ul></ul><ul><ul><li>this is called increasing entropy </li></ul></ul><ul><ul><ul><li>entropy is the amount of disorder (chaos) in a system and as long as there is continuous energy transfer, entropy remains low. </li></ul></ul></ul><ul><ul><ul><li>laws of thermodynamics </li></ul></ul></ul><ul><ul><ul><li>second law of thermodynamics </li></ul></ul></ul>
  • 9. 2 nd law in relation to biology <ul><li>Energy in living organisms is used for growth, repair, motion etc. </li></ul><ul><li>If this energy is constantly used for these things, without any input of more energy, the organism will die. </li></ul><ul><ul><ul><li>laws of thermodynamics </li></ul></ul></ul><ul><ul><ul><li>second law of thermodynamics </li></ul></ul></ul>
  • 10. Third law of thermodynamics <ul><li>states that if all the molecules in the universe stopped moving (a natural thing that molecules do), a state called absolute zero would occur </li></ul><ul><li>this would happen when all matter and energy is randomly distributed in the universe (highest entropy) </li></ul><ul><li>would equal -273.15 deg. Celsius </li></ul>

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