CH40 – “H” is for “Henthalpy”
- P4 – Wednesday, April 25th
- P5 – Thursday, April 26th
- P7 – Friday, April 27th
- 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
- 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)
- 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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