A Composition of carbon dioxide, oxygen and nitrogen with mole ratio 1:2:5 with 4 moles of oxygen, enters a reactor with a flow rate of 100 kg/s, the ratio of rates of leaving the reactor of the three is 5:2:1, and 5 moles of nitrogen leaves the reactor, what is the total number of moles leaving the reactor?

Correct Answer: 6.2
number of moles of carbon dioxide, oxygen and nitrogen are 2, 4 and 10 respectively, let the leaving flow rates of carbon dioxide, oxygen and nitrogen are 5y, 2y and y respectively, => for nitrogen, 10*100 = y*5 => y = 200 kg/s, => for oxygen, 4*100 = 400*n => n = 1, for carbon dioxide, 2*100 = 1000*n => n = 0.2, => total number of moles leaving the reactor = 5 + 1 + 0.2 = 6.2.