l. [5 marks] 'Weill consider the space inside an oven as our system, for this problem: it's an open, system, so gas can ow in and out of it; the system consists of whatever gas molecules are inside the oven at an}r given time. The oven is initially closed, with its volume of V1 = 1.00 n13 full of air at a temperature of T1 = 180. C at a pressure of P1 = 1.535 aim; state 1 is (P1. V1. n1. T1). with internal energy U1. The oven door is then opened. allowing the hot air to escape. and the oven then sits open and cools down until it ends up lled with air (still with a volume of V2 2 1.00 mg) at a temperature of T2 = 22.0 G0 and a pressure of P2 = 0.980 aim; state 2 is (Fri/2.712.312). with internal energ}r U2. Treating air as a diatomic ideal gas, nd the change in internal energyr for this system, between state 1 and state 2: AU 2 U U1 [in kiloJoules. to three s.f.]