Question

The fractional change in volume of a system for variable volume systems, expressed in terms of the number of moles is ____

(a) ε = \(\frac{Change \, in \, number \, of \, moles \, of \, the \, reaction \, system \, when \, the \, reaction \, is \, complete}{Total \, number \, of \, moles \, fed} \)

(b) ε = \(\frac{Total \, number \, of \, moles \, fed}{Change \, in \, number \, of \, moles \, of \, the \, reaction \, system \, when \, the \, reaction \, is \, complete} \)

(c) ε = \(\frac{Number \, of \, moles \, left \, when \, the \, reaction \, is \, complete}{Total \, number \, of \, moles \, fed} \)

(d) ε = \(\frac{Total \, number \, of \, moles \, fed}{Number \, of \, moles \, left \, when \, the \, reaction \, is \, complete} \)

This question was posed to me by my school teacher while I was bunking the class.

The question is from Stoichiometry topic in chapter Rate Laws and Stoichiometry of Chemical Reaction Engineering

Answer 1

Right option is (a) ε = \(\frac{Change \, in \, number \, of \, moles \, of \, the \, reaction \, system \, when \, the \, reaction \, is \, complete}{Total \, number \, of \, moles \, fed} \)

To elaborate: ε is the fractional change in volume of the reaction system between no conversion and complete conversion of the reactant. It is the ratio of the change in moles of the reaction mixture to achieve complete conversion to the number of moles fed initially.