Question

An unsteady state system, the flow in the rate of A is 12 mole/s, what is the flow out rate of B if the accumulation was 18 mole in 3 seconds?

(a) 4 mole/s

(b) 6 mole/s

(c) 8 mole/s

(d) 9 mole/s

The question was asked by my college professor while I was bunking the class.

My doubt stems from Steady-State and Unsteady-State Systems topic in portion Introduction to Material Balances of Basic Chemical Engineering

Answer 1

Correct choice is (b) 6 mole/s

To explain: Flow rate of B = 12 – 18/3 = 6 mole/s.