Question

In a reactor two stream are entering, one with N2 at 10 atm and 27^oC, and another with O2 at 10 atm and 0^oC, producing NO, NO2, NO3, and O2 at 10 atm and 23^oC, what are the total degrees of freedom?

(a) 12

(b) 17

(c) 19

(d) 21

This question was posed to me during an interview for a job.

My question comes from Degrees of Freedom Analysis topic in portion Energy Balances that Include the Effects of Chemical Reaction, Ideal Processes, Efficiency and the Mechanical Energy Balance and Heats of Solution and Mixing of Basic Chemical Engineering

Answer 1

Correct option is (c) 19

Easy explanation: Total species = 1 + 1 + 4 = 6, total stream flows = 3, stream pressures = 3, stream temperatures = 3, heat released = 1, and extent of reaction = 3, => degrees of freedom = 6 + 3 + 3 + 3 + 1 + 3 = 19.