An ideal gas with CP = (7/2)R and molecular mass of 28 g/mol enters an adiabatic, steady state valve at T = 500 K and P = 0.5 MPa. The entering and exiting streams both have negligible velocity. What are the temperature and pressure of the exiting stream?
A. T = 500 K, P = 0.1 MPa
B. T = 500 K, P cannot be determined from the given information.
C. T = 450 K, P = 0.1 MPa
D. T = 450 K, P cannot be determined from the given information.
E. Neither T nor P can be determined from the given information.
A. Incorrect. Your energy balance is correct, but something else is wrong.
B. Correct. We know using Equation 3.119 that inlet enthalpy is equal to outlet enthalpy. For an ideal gas, enthalpy is a function of temperature alone, so we cannot make any conclusions about outlet pressure other than it will be less than or equal to inlet pressure.
C. Incorrect. Your energy balance is incorrect and you are making a bad assumption.
D. Incorrect. Your energy balance is wrong, but you are correct about pressure.
E. Incorrect. At least one of these properties can be calculated from the given information.
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