1 / 15

Energy & Chemical Change

Energy & Chemical Change. Energy – The ability to do work Potential Energy – due to composition or position Kinetic Energy – Due to motion Law of Conservation of Energy – In a chemical reaction energy can be converted from one form to another, but it is neither created or destroyed.

lotte
Download Presentation

Energy & Chemical Change

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Energy & Chemical Change • Energy – The ability to do work • Potential Energy – due to composition or position • Kinetic Energy – Due to motion • Law of Conservation of Energy – In a chemical reaction energy can be converted from one form to another, but it is neither created or destroyed

  2. Chemical potential energy – the energy stored in a substance because of its composition • Heat – a measure of the amount of energy flowing from a warmer object to a cooler object

  3. Units of Heat • Calorie – the heat needed to raise the temperature of 1 gram of water 1oC • Calorie – nutritional calorie = 1,000 c • SI Unit = Joule 1c = 4.184 J • BTU – British Thermal Unit – the heat needed to raise 1 lb of water 1oF

  4. Specific Heat – c – amount of heat needed to raise the temperature of 1 g of a substance 1oC • For water – c = 1c/goC = 4.184J/goC

  5. Formula for the amount of heat transferred q = mc t • q = heat, m = mass, c = specific heat and t = change in temperature

  6. Calorimeter – an insulated device for measuring the amount of absorbed or released heat during a chemical or physical process • Exothermic reaction - heat is released • Endothermic reaction – heat is absorbed

  7. Enthalpy - H = change in energy • Hrxn = Hproducts - Hreactants • Exothermic = negative H • Endothermic = positive H

  8. Molar Enthalpy of Vaporization - Hvap - energy required to vaporize 1 mole of a substance at its boiling point • Molar Enthalpy of Fusion - Hfus – energy required to melt 1 mole of a substance at its melting point

  9. Hess’s Law – If 2 or more chemical equations can be added to produce a final equation, the sum of the enthalpy changes for the individual reactions is the enthalpy change for the final reaction.

  10. Standard Enthalpy of Formation - Hf – the change in enthalpy in the formation of one mole of the compound from its constituent elements • Each free element in its standard state has a Hf = 0

  11. Spontaneous process – a physical or chemical change that occurs without outside intervention • Entropy – S – a measure of the disorder or randomness • Law of Disorder – spontaneous processes always proceed in a direction to increase the disorder of the universe - S is positive

  12. Predicting Entropy Changes • Entropy increases when a solid changes to a liquid or a liquid changes to a gas • Entropy decreases when a gas dissolves in a liquid • Entropy increases when the number of gaseous product particles is greater than the number of gaseous reactant particles

  13. Usually the solvation of solids or liquids increases the entropy • Entropy is increased whenever the temperature of a substance is increased

  14. Gibbs free energy = G = H – T S • Reaction is spontaneous when G is negative

  15. Job Skills for the Future • Evaluate and Analyze • Think Critically • Solve Math Problems • Organize and Use References • Synthesize Ideas • Apply Ideas to New Areas • Be Creative • Make Decisions with Incomplete Information • Communicate in Many Modes Chemistry will develop ALL of these skills in YOU!

More Related