1 / 129

Thermo-chemistry

Drill: Calculate the volume of gas released at 227 o C under 83.1 kPa pressure when 320 kg of NH 4 NO 3 is exploded forming N 2 , O 2 , & H 2 O: . Thermo-chemistry. AP Chm. Chapter 8. Chm II. Chapter 15. Thermochemistry. The study of heat transfer in chemical reactions.

freja
Download Presentation

Thermo-chemistry

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. Drill: Calculate the volume of gas released at 227oC under 83.1 kPa pressure when 320 kg of NH4NO3 is exploded forming N2, O2, & H2O:

  2. Thermo-chemistry

  3. AP Chm Chapter 8

  4. Chm II Chapter 15

  5. Thermochemistry • The study of heat transfer in chemical reactions

  6. Thermochemistry Topics • Heat change • Calorimetry • Thermo-Chm-Eq

  7. Thermo-chemical Terms

  8. Heat (H) • A form of energy that can flow between samples of matter

  9. Heat cannot be measured directly; thus, we measure heat change (DH)

  10. Enthalpy • Another name for heat H

  11. Enthalpy Change • Heat that can flow in/out of a system DH

  12. System • That part of nature upon which attention is focused

  13. Surroundings • That part of nature around the part upon which we are focused

  14. Reaction Coordinate • A graph of energy change versus time in a chemical reaction

  15. P Energy R Time

  16. Exothermic Rxn • Chemical reactions that release, give off heat, or lose heat

  17. Exothermic Rxn • Products will contain less heat than the reactants DH < 0

  18. Endothermic Rxn • Chemical reactions that absorb, take in heat, or gain heat

  19. Endothermic Rxn • Products will contain more heat than the reactants DH > 0

  20. Topic: Heat Change

  21. Specific Heat • The heat required to raise one gram of a substance 1oC • C: (J/goC, J/kgoK)

  22. Specific Heat Formula DH = mCDT

  23. Heat of Fusion • The heat required to melt one gram of a substance at its normal MP • Hf: (J/g or J/kg)

  24. Heat of Fusion Formula DH = mHf

  25. Heat of Vaporization • The heat required to boil one gram of a substance at its normal BP • Hv: (J/g or J/kg)

  26. Heat of Vap. Formula DH = mHv

  27. AP CHM HW • Read: Chapter 8 • Work problems: 5 & 17 • Page: 234

  28. CHM II HW • Read: Chapter 9 • Work problems: • Page:

  29. Calculate the heat change when 10.0 g H2O goes from –100.0oC to 200oC.MP = 0oC BP = 100oCHf = 334 J/g HV = 2260 J/g Cice = 2.06 J/gK Cwater = 4.18 J/gK Csteam = 2.02 J/gK

  30. Drill: Calculate the heat required to change 25 g of water from 140.0oC to 60.0oC MP = 0oC BP = 100oCHf = 334 J/g HV = 2260 J/g Cice = 2.06 J/gK Cwater = 4.18 J/gK Csteam = 2.02 J/gK

  31. Topic: Calorimetry

  32. Calorimetry • A method to measure the experimental heat transfer in a system

  33. Calorimeter • Device used to measure heat transfer • A calorimeter is an adiabatic system • Experimental yield

  34. Adiabatic System • A system that exchanges zero heat with its surroundings DHsystem = 0

  35. DH (J or kJ) DH = q = the heat or enthalpy change in a system DHsys = mcDTsysparts

  36. Calorimetry DHsystem = 0 DHsys = DHcal + DHrxn DHrxn = -DHcal DHrxn = -mcDTcal

  37. When Q reacts in a 1.5 kg calorimeter containing 2.5 kg water the temp changes from 22.5oC to 26.5oC.Calculate DHrxn. Cwater = 4.18 J/gK Ccal = 2.00 J/gK

  38. Chm II HW Problems: 64 & 65 Page: 641-641

  39. AP Chm HW Problems: 8 & 9 Page: 234

  40. When X reacts in a 2.0 kg calorimeter containing 1.5 kg water, the temp changes from 22.5oC to 30.5oC. Calculate DHrxn. Cwater = 4.18 J/gK Ccal = 1.50 J/gK

  41. When Z reacts in a 1.0 kg calorimeter containing 2.0 kg water, DT = 22.5oC to 32.5oC. Calculate DHrxn. Cwater = 4.18 J/gK Ccal = 2.00 J/gK

  42. Drill: When 40.0 g NH4NO3 dissolves in 460.0 g water at 25.0oC, the temp. falls to 22.5.oC. Calculate the DHosoln for NH4NO3. Csoln = 4.00 J/gK

  43. Topic: Thermochemical Equation (TCE)

  44. Thermo-chemical Equation Terms

  45. Heat of Reaction • The heat or enthalpy change of a chemical reaction DHrxn

  46. Typical Reaction • HCl + NaOH  NaCl + HOH

  47. Heat of Solution • The heat or enthalpy change when a substance is dissolved DHsoln

  48. Typical Ionization KCl  K+(aq) + Cl-(aq)

  49. Heat of Combustion • The heat or enthalpy change when a substance is burned DHcombustion

  50. Combustion Reaction • CxHy + O2 • CO2 + HOH

More Related