T-L03 Work, Heat and 1^st Law of Thermodynamics

Preamble (Review)

1. Phase Diagrams (P vs T)
   
2. Music - Quarks
3. Review Lecture nt02
4. Heat vs Temperature Julius Sumner Miller

Key Points

• Δ E_sys = Δ K + Δ U + ΔE_th = W + Q   (1^st law)
• K, U, E are nouns! W and Q are verbs!
• NB: W ≡ W_ext (Work done on system, Heat transfered to system is positive)
• W = ∫ Fds = ∫ pAds = ∫ pdV
• Molar Specific Heat Capacity: Δ E_th= n C Δ T
    C [J mol^-1 K^-1]
• Heat of Transformation: Q = ± ML [J kg^-1]
    (Phase change, Δ P = Δ V = 0)
• Ideal Gases
  • pV Diagram (p vs V: 2 of 4 state variables, nRT=pV)
  • Processes: Work (Path Dependent)
    • isochoric: V_f = V_i → W = 0
    • isobaric: p_f = p_i → W = -p Δ V
    • isothermal: T_f = T_i → W = -nRT ln (V_f / V_i )
        (NB: nRT=p_iV_i =p_fV_f)
  • Processes: Heat (Path Dependent)
    • isochoric: W=0 → Δ E_th= Q = n C_v Δ T
    • isobaric: → Q = n C_p Δ T → W = n (C_v - C_p) Δ T
    • isothermal: Δ E_th=0
    • adiabatic: Q=0 → Δ E_th= W = n C_v Δ T
• Heat-Transfer Mechanisms
  • Conduction
  • Convection
  • Radiation

PowerPoint Presention

Knight Chapter 19 Work, Heat and 1st Law of Thermodynamics(Slides)

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