FÍSICA

4 LISTA FISICA II (P2)
1) Um pistão com embolo móvel contém 2 mols de O2 e recebe 581J de calor. O gás sofre uma expansão isobárica na qual seu volume aumentou de 1,66l, a uma pressão constante de 105N/m2. Considerando que nessas condições o gás se comporta como gás ideal, utilize R=8,3 J/mol K e calcule
a) a variação de energia interna do gás

______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ n = 2mols Q1=581J P = 105 N/m2
Q = ∆v + w  w = P . ∆v  w = 105 . 1,66x10-3  w = 166 J
Q = ∆u + w  581 = ∆u +166  ∆u = 518 – 166  ∆u = 415 J
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b) variação de temperatura do gás

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P . v = nRT P1 = P2
Pv2 – Pv1 = nRT2 – nRT1  P(v2-v1) = nR(T2-T1)  P. ∆v = nR∆T  105 .