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CH40 – “H” is for “Henthalpy”

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Dates

  • P4 – Wednesday, April 25th
  • P5 – Thursday, April 26th
  • P7 – Friday, April 27th

Lab Recap

  • what did you determine for “c” ?
  • what identity did you determine for the metal?
  • what factors introduced uncertainty?
  • how might they have impacted the result?
  • Q: what type of report would you like to submit?

New Idea – Enthalpy

  • defined: H = E + PV
  • not really meaningful
  • useful definition: ΔH = Qp
  • enthalpy: think of this as the energy associated with a process
  • enthalpy: think of this as “chemical energy” of formula
  • reaction energy
  • physical changes
  • calorimetry
  • H is a state function
  • ΔH + means endothermic process
  • ΔH – means exothermic process

Examples of Enthalpy

  • ΔHrxn = “heat” of a reaction
  • ΔHsolv = “heat” of solvation
  • ΔHf = “heat” of formation
  • ΔHcomb = “heat” of combustion

Enthalpy and Moles

  • ΔH is a molar quantity related to quantity
  • Example: Ch. 6 (42)

Enthalpy and Calorimetry

  • reaction inside a caloriometer
  • ΔH then confined inside
  • ΔH –> Q inside calorimeter
  • Example: Ch. 6 (62)

Homework

  • Work on the lab report
  • details agreed upon in class

Heads Up: Test Wed/Thu Next Week

  • we did not test separately on acids and bases
  • the next test will incorporate these ideas into the questions
  • the course is slowly reaching convergence of all concepts from the first and second semester combined… THE CONVERGENCE IS COMING!

 

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This entry was posted on April 25, 2018 by in 1718 and tagged , , , , , .

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