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Energy

Energy. Chap. 16. Definitions. Definitions. Energy. Energy is the ability to do work or produce heat. Definitions. Energy Heat. Heat is energy moving from one place to another. Heat = Energy. For us, these terms will be used synonymously. Definitions. Energy Heat Temperature.

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Energy

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  1. Energy Chap. 16

  2. Definitions

  3. Definitions • Energy Energy is the ability to do work or produce heat

  4. Definitions • Energy • Heat Heat is energy moving from one place to another

  5. Heat = Energy For us, these terms will be used synonymously

  6. Definitions • Energy • Heat • Temperature A measure of the kinetic energy of the particles in a substance

  7. Definitions • Energy • Heat • Temperature • Endothermic A description of a process that absorbs heat

  8. Definitions • Energy • Heat • Temperature • Endothermic • Exothermic A description of a process that gives off heat

  9. Types of Energy • Kinetic Energy of motion

  10. Types of Energy • Kinetic • Mechanical Moving objects

  11. Types of Energy • Kinetic • Mechanical • Thermal Heat energy (moving particles)

  12. Types of Energy • Kinetic • Potential Stored energy

  13. Types of Energy • Kinetic • Potential • Gravitational Energy that can be released as gravity acts

  14. Types of Energy • Kinetic • Potential • Gravitational • Chemical Energy stored in chemical bonds

  15. Types of Energy • Kinetic • Potential • Radiant Energy in the form of light

  16. Measuring Heat (q)

  17. Measuring Heat (q) • Units

  18. Measuring Heat (q) • Units • joule SI unit of energy (work). Work done by applying one Newton force over one meter.

  19. Measuring Heat (q) • Units • joule • calorie Energy required to heat one gram of water by 1° C.

  20. Measuring Heat (q) • Units • joule • calorie • Calorie A nutritional calorie. 1 Cal = 1000 cal

  21. Measuring Heat (q) • Units • joule • calorie • Calorie • kilocalorie Equivalent to calories

  22. Measuring Heat (q) • Units • joule • calorie • Calorie • kilocalorie Equivalent to 1000 calories

  23. Measuring Heat (q) • Units • joule • calorie • Calorie • kilocalorie • BTU Energy required to heat 1 lb. water by 1º F.

  24. Heat Unit Conversions 1 cal = 4.184 J 1000 cal = 1 Cal = 1 kcal

  25. Self Check – Ex. 1 A reaction produces 3800 J of heat. How many calories is this?

  26. Self Check – Ex. 2 A can of soda contains 150 Calories. How many joules of energy is this?

  27. Measuring Heat (q) • Units • Heat is related to temperature

  28. Measuring Heat (q) • Units • Heat is related to temperature Temp. = 35º C Temp. = 65º C Beaker #1 Beaker #2 Which has more heat?

  29. Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . .

  30. Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Mass of material

  31. Which beaker could melt more ice (which has more heat)? T2 = 85º C T1 = 85º C Beaker #1 Beaker #2

  32. Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Mass of material • Type of material

  33. Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat Amount of heat required to raise the temperature of 1 gram of substance by 1º C

  34. Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat • Some material takes a lot of energy to raise its temperature

  35. Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat • Some material takes a lot of energy to raise its temperature • Some material takes less

  36. Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat • Some material takes a lot of energy to raise its temperature • Some material takes less • For water it’s 1 calorie/g ºC

  37. Specific Heat Table SubstanceSpec. Heat (c) Water 4.184 J/g ºC Aluminum 0.89 J/g ºC Iron 0.45 J/g ºC Copper 0.387 J/g ºC Silver 0.24 J/g ºC Gold 0.129 J/g ºC Lead 0.l28 J/g ºC

  38. Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat • Calculation q = m x c x∆T

  39. Self Check – Ex. 3 How much heat must be applied to a 25 g chunk of iron to raise its temperature by 100ºC? (ciron = 0.45 J/g ºC)

  40. Self Check – Ex. 4 How much heat must be applied to a 25 g sample of water to raise its temperature by 100ºC? (ciron = 4.18 J/g ºC)

  41. Bond Energy

  42. Bond Energy • When bonds are broken energy is . This is endothermic

  43. Bond Energy • When bonds are broken energy is required. (positive) This is endothermic

  44. Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is .

  45. Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is released. (negative) This is exothermic

  46. Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is released. (negative) • The sum of the bond energies gives an estimate of the reaction energy

  47. Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is released. (negative) • The sum of the bond energies gives an estimate of the reaction energy • Positive values = endothermic

  48. Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is released. (negative) • The sum of the bond energies gives an estimate of the reaction energy • Positive values = endothermic • Negative values = exothermic

  49. Self Check – Ex. 5 Draw Lewis structures for each substance and calculate the energy for the reaction below. 2CO + O2 2CO2

  50. Enthalpy Stoichiometry

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