Please answer the question with mentioning: Represent / Interpret / Develop / Ev

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Please answer the question with mentioning: Represent / Interpret / Develop / Evaluate / Assess

Problem 1 (CQ) (Problem 17.39 (c)): A 3000 mL flask is initially open in a room containing air at 1.00 atm and 20°C. The flask is then closed and immersed in boiling water. When the air in the flask has reached thermodynamic equilibrium, the flask is opened and air is allowed to escape. The flask is then closed and cooled back to 20°C. Find the final pressure in the flask. REPRESENT: V1-3.00 L, p,-1.00 atm, T1-293 K, T2= 373K, R = 0.0821 Latm/ (mol:K): p,-? Make a sketch of four states of the gas INTERPRET: 1) The problem involves air ideal gas 2) FOUR states are mentioned DEVELOP

Explanation / Answer

Initial condition
P1 = 1 atm = 101.3 kPa ,V1 = 3 L , T1 = 293 K
R = 8.314 J/mol k
Now flask is closed therefore the volume will be constant
hence
P1 /T1 = Constant from ideal gas equation
P2 /T2 = P1 /T1
P2 = (T2/T1)*P1 = (373/293)*101.32 = 128.984 kPa
Now again the flask is opened , therefore the pressure rached to the P1 and temperature would be 373 K
hence the no. of moles remain in the flask after opening it
PV = nRT
n = P1V /RT2 = 101.32*103*(3*10-3) /(8.314*373)
V = 3 L = 3*10-3 m3
n = 0.0979 mol.
hence these would be the no. of moles of air when flask will be closed again.
Now it has been cooled to 20 C = 293 K , therefore
P4V = nRT4
P4*(3*10-3) = 0.0979*8.314*293
P4 = 79.49*103 Pa = 79.49 kPa

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