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09 - Consider two cases 1 ideal monatomic gas(ar He 2 ideal...

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Chapter 9 8/27/09 ∆E = q + w ∆E results from changes in the heat content and/or the work done on or by the system q+ endothermic q- exothermic w+ work done on the system w- work done on the surroundings Common form of work: pressure-volume changes P= F/A Piston moves a distance ∆h against pressure P does work on the surroundings Area x distance (∆h) = volume F = P x A -w = P x A x ∆h -w = P ∆V w = -P ∆V For reaction carried out at constant P, the work performed by the system can be expressed in terms of V changes in the system ∆H (-) heat lost by system ∆H (+) heat gained by system How do ∆H and ∆E change when there is a change in T,P, or V for an ideal gas?
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Unformatted text preview: Consider two cases: 1) ideal monatomic gas (ar, He) 2) ideal polyatmic gas (N 2 , CO, CH 4 ) What is the relationship of ∆E + ∆H to T? How much heat must be added to raise the T of an ideal gas? Consider heating at constant volume: ∆E = q v + w w = P∆V = 0 ∆E = q v Adding heat to a closed system all the heat to the closed system goes into increasing the translational energy of the gas molecules Translational E increases P increases (KE) avg = n(3/2)RT Translational E is proportional to T ∆(KE)avg = ∆E = qv = n(3/2)RT R= 8.3145 J/K mol Molar Heat Capacity : the heat required to raise the T of 1 mol of a substance by 1 K...
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