Question

An unsteady state system, the flow in rate of A is 8 mole/s, what is the flow out rate of B if the accumulation was 6 mole in 2 seconds?

(a) 1 mole/s

(b) 2 mole/s

(c) 3 mole/s

(d) 5 mole/s

The question was asked in final exam.

The origin of the question is Steady-State and Unsteady-State Systems in portion Introduction to Material Balances of Basic Chemical Engineering

Answer 1

Right answer is (d) 5 mole/s

The explanation: Flow rate of B = 8 – 6/2 = 5 mole/s.