1 / 90

Thermo-chemistry

Calculate the volume of gas released at 227 o C under 83.1 kPa pressure when 16 kg of NH 4 NO 3 is exploded forming N 2 , O 2 , & H 2 O:. Thermo-chemistry. Thermochemistry. The study of heat transfer in chemical reactions. Thermochemistry. Heat change Calorimetry TCE.

akiva
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. Calculate the volume of gas released at 227oC under 83.1 kPa pressure when 16 kg of NH4NO3 is exploded forming N2, O2, & H2O:

  2. Thermo-chemistry

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

  4. Thermochemistry • Heat change • Calorimetry • TCE

  5. Thermo-chemical Terms

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

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

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

  9. P Energy R Time

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

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

  12. Heat Change

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

  14. Sp. Heat DH = mCDT

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

  16. Heat of Fusion DH = mHf

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

  18. Heat of Vap. DH = mHv

  19. 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

  20. 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

  21. Calorimetry • Experimental measure of heat transfer

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

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

  24. DH (J) DH = q = the heat or enthalpy change in a system DHsys = mCDTsysparts

  25. Calorimetry DHsystem = 0 DHsys = DHcal + DHrxn DHrxn = -DHcal DHrxn = -mCDTcal

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

  27. When X reacts in a 2.0 kg calorimeter containing 1.5 kg water went from 22.5oC to 30.5oC. Calculate DHrxn. Cwater = 4.18 J/gK Ccal = 1.50 J/gK

  28. Homework • Problems 7 & 8 • On page 234

  29. Thermo-chemical Equation Terms

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

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

  32. Typical Ionization HCl  H+(aq) + Cl-(aq)

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

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

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

  36. Rxn Making Cpds from ele H2 + ½ O2 H2O

  37. Heat of Formation • The heat required to form one mole of a compound from pure elements DHfo (kJ/mole)

  38. The Degree Symbol • Indicates standard conditions & molar quantities by itself or from a balanced equation.

  39. Enthalpy • Heat flow in a system DH

  40. Gibb’s Free Energy • Energy of a system that can be converted to work • Determines spontaneity DG

  41. Energy of Formation • The energy required to form one mole of a compound from pure elements DGfo (kJ/mole)

  42. Exergonic Reaction • A reaction in which free energy is given off DG< 0

  43. Endergonic Reaction • A reaction in which free energy is absorbed DG> 0

  44. Exergonic Reaction • A reaction which can be spontaneous DG< 0

  45. Endergonic Reaction • A reaction which cannot be spontaneous DG> 0

  46. Reaction at Equilibrium DG= 0

  47. Interrelation Term (DG) DG interrelates thermochemistry, chemical equilibria, & electrochemistry

  48. Entropy • A measure of disorder DSo

  49. Entropy of Formation • The entropy of one mole of a substance • Sfo (J/moleoK)

  50. Drill: Define: • Heat of reaction • Heat of solution • Heat of formation • Energy of formation • Entropy of formation

More Related