A reaction from unknown reactants (R) : `R rarr P` is molar entropy of the products (P) is measured to be 460 J/mol K, and 71.3 kJ of heat was given off in the process to the surroundings when 1 mol reacted, then the molar entropy of the reactants has to be

Options

A. at least -230 J/mol K
B. at the most 690 J/mol K
C. at the most 230 J/mol K
D. at the least 690 J/mol K

Answer

B

Explanation

Let us solve this at boundary condition of `Delta G^(@) = 0`
`Delta S^(@) = (Delta H^(0))/(T) = (-71.3 xx 1000)/(310) = -230 JK^(-1)`
`rArr -230 JK^(-1) = S_(m)^(0) (R) = 460 JK^(-1) - S_(m)^(0) (R)`
`rArr S_(m)^(0) (R) = 690 JK^(-1)`. It is the maximum value of entropy which the reactant can have. If `S_(m)^(0) gt 690 JK^(_1) mol^(-1), Delta G^(0) gt 0`