Question

Solution-1 containing 30% acetic acid and 20% nitrogen at the rate 10 Kg/min combines with Solution-2 containing 20% acetic acid and 10% nitrogen at the rate 20 Kg/min and Solution-3 containing 10% acetic acid and 30% nitrogen at the rate N the product formed contains 20% acetic acid at the rate P, what is the percentage of nitrogen in product?

(a) 10%

(b) 17.5%

(c) 25.5%

(d) 32.5%

The question was posed to me in class test.

Question is taken from Problem Solving Strategy in portion A General Strategy for Solving Material Balance Problems and Solving Material Balance Problems for Single Units of Basic Chemical Engineering

Answer 1

Correct option is (b) 17.5%

To explain I would say: The equations for material balance, P = F + D + N = 30 + N, and 0.3(10) + 0.2(20) + 0.1N = 0.2P = 0.2(30 + N), => N = 10 Kg/min, => P = 40 Kg/min, equation of material balance for nitrogen: 0.2(10) + 0.1(20) + (0.3)10 = y(40), => y = 7/40 = 0.175, => Percentage of nitrogen in the product is 17.5%.