Question

A reactor is supplied with two steams with equal flow rates, stream-1 containing 75% SO2, 25% N2 and stream-2 containing pure H2S, if the product has 1200 grams of S, and the ratio of H2S to H2O is 5 and the ratio of SO2 to H2S is 2, how many moles of water are produced?

(a) 1

(b) 2

(c) 3

(d) 4

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This interesting question is from Species Material Balances topic in section The Chemical Reaction Equation & Stoichometry, Material Balances for Processes Involving Reaction and Multiple Units of Basic Chemical Engineering

Answer 1

The correct choice is (a) 1

Explanation: The reaction is 2H2S + SO2 -> 3S + H2O, => extent of reaction, E = (1200/32)/3 = 12.5, Let the rate be F. nSO2p = 2nH2Sp, => 0.75F – E = 2(F – 2E), => 1.25F = 3(12.5), => F = 30 moles. 5nH2Op = nH2Sp, => 5 nH2Op = 30 – 2(12.5) = 5, => nH2Op = 1.