Dunnoe Essay
2528 Words
Jun 17th, 2014
11 Pages
Chapter 6 — Thermo — Part 1
1
1
Chapter Scopes
• Endothermic & Exothermic reactions • Enthalpy changes: H of formation, combustion, hydration, neutralization, atomization. • Lattice energy, electron affinity • Heat of fusion and vaporization • Hess’ Law • BornHaber cycles • Calorimetry
2
CHAPTER 5
Chemical Energetic / Thermochemistry
© 2006 Brooks/Cole  Thomson
© 2006 Brooks/Cole  Thomson
3
Energy & Chemistry
• ENERGY is the capacity to do work or transfer heat. • HEAT is the transfer of thermal energy between two objects because of their difference in temperature. Other forms of energy light electrical kinetic and potential
© 2006 Brooks/Cole  Thomson
Thermochemistry
• Thermochemistry is the study of …show more content…
1
1
Chapter Scopes
• Endothermic & Exothermic reactions • Enthalpy changes: H of formation, combustion, hydration, neutralization, atomization. • Lattice energy, electron affinity • Heat of fusion and vaporization • Hess’ Law • BornHaber cycles • Calorimetry
2
CHAPTER 5
Chemical Energetic / Thermochemistry
© 2006 Brooks/Cole  Thomson
© 2006 Brooks/Cole  Thomson
3
Energy & Chemistry
• ENERGY is the capacity to do work or transfer heat. • HEAT is the transfer of thermal energy between two objects because of their difference in temperature. Other forms of energy light electrical kinetic and potential
© 2006 Brooks/Cole  Thomson
Thermochemistry
• Thermochemistry is the study of …show more content…
• The heat (q) “lost” or “gained” is related to a) sample mass b) change in T and c) specific heat capacity
Specific heat capacity = heat lost or gained by substance (J) (mass, g)(T change, K)
© 2006 Brooks/Cole  Thomson
11
Change in Temperature (T)
∆T of System Increase Sign of ∆Tsystem + Tfinal >Tinitial Tfinal < Tinitial Sign of q + Direction of Heat Transfer Heat transferred from surroundings to system (_____thermic) Heat transferred from system to surroundings (_____thermic)
12
Decrease

© 2006 Brooks/Cole  Thomson
Chapter 6 — Thermo — Part 1
3
13 14 Example 1: If 25.0 g of Al cool from 310oC to 37oC, how many joules of heat energy are lost by the Al?
Heat Transfer q = m x Cs x ∆T q = C x ∆T
• • • • • q = heat absorbed or released (J) Cs = specific heat (J g1 K1) C = heat capacity (J K1) m = mass of substance (g) ∆T = change in temperature (K) = Tfinal  Tinitial
(specific heat capacity of Al = 0.897 J g1 K1)
Solution: Heat gain/lose = q = (sp. ht.)(mass)( T) where T = Tfinal  Tinitial q= q=
Negative sign on q signals heat “lost by” or “transferred OUT” from
Specific heat capacity = heat lost or gained by substance (J) (mass, g)(T change, K)
© 2006 Brooks/Cole  Thomson
11
Change in Temperature (T)
∆T of System Increase Sign of ∆Tsystem + Tfinal >Tinitial Tfinal < Tinitial Sign of q + Direction of Heat Transfer Heat transferred from surroundings to system (_____thermic) Heat transferred from system to surroundings (_____thermic)
12
Decrease

© 2006 Brooks/Cole  Thomson
Chapter 6 — Thermo — Part 1
3
13 14 Example 1: If 25.0 g of Al cool from 310oC to 37oC, how many joules of heat energy are lost by the Al?
Heat Transfer q = m x Cs x ∆T q = C x ∆T
• • • • • q = heat absorbed or released (J) Cs = specific heat (J g1 K1) C = heat capacity (J K1) m = mass of substance (g) ∆T = change in temperature (K) = Tfinal  Tinitial
(specific heat capacity of Al = 0.897 J g1 K1)
Solution: Heat gain/lose = q = (sp. ht.)(mass)( T) where T = Tfinal  Tinitial q= q=
Negative sign on q signals heat “lost by” or “transferred OUT” from