2012 Study-Guide-1(1)

Know how to derive these quantities for reversible

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Unformatted text preview: $ ∂x ' y $ ∂y ' z %( $ ∂x ' z € € 3) Transformations For n Moles of an Ideal Gas Between States A and B: Calculation of work, heat, change in internal energy and change in enthalpy for processes on ideal gases that are either isobaric, isochoric or isothermal. Know how to derive these quantities for reversible isothermal expansion/compression processes (P = Pext) and for expansion/compression processes under constant external pressure. Know how to relate initial to final state variables (P, V, T) for each of these processes. All equations of interest are given on page 3. Isochoric Heating / Cooling: VA = VB (Only T and P vary) PA / T A = PB / T B ΔU = CV (TB - TA) = n CVm (TB - TA) ΔH = CP (TB - TA) = n CPm (TB - TA) q = ΔU w=0 Isobaric Heating / Cooling: PA = PB (P = Pext = constant) (Only T and V vary) V A / TA = V B / TB ΔU = CV (TB - TA) = n CVm (TB - TA) ΔH = CP (TB - TA) = n CPm (TB - TA) q = ΔH w = ΔU - q = ΔU - ΔH = - nR (TB - TA) = - PB (VB - VA) Isothermal Compression / Expansion: TA = TB (Only P and V vary) PA V A = PB V B ΔU = CV (TB - TA) = 0 ΔH = CP (TB - TA) = 0 q=-w w = - Pext (VB - VA) for expansion/compression at constant external pressure w = - nRTA ln (VB / VA) for reversible expansion/compression (P = Pext = variable) 4) Relationship between Δ H and Δ U for any process: Be able to re-derive that: Δ H = Δ U + RT Δ n for an isothermal process involving a change in the number of moles of gas by Δng Δ H = Δ U + nR Δ T for the heating or cooling of an ideal gas involving no change in the number of moles of gas (closed system). Δ H = Δ U + p Δ V for any isobaric process. Δ H = Δ U + V Δ p for any isochoric process....
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