Question

A gas mixture input is given to a membrane with 20% O2 and 80% N2, the waste contains 60% of the input and the product contains 30% O2 and 70% N2, what are the number of moles of O2 in the waste?

(a) 1

(b) 2

(c) 3

(d) Can’t be determined

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This is a very interesting question from Solving Material Balance Problems for Single Units topic in section A General Strategy for Solving Material Balance Problems and Solving Material Balance Problems for Single Units of Basic Chemical Engineering

Answer 1

Correct choice is (d) Can’t be determined

Easiest explanation: Since the amount of input is not given, number of moles of O2 cannot be determined.