Consider the following three gas-phase reactions and assume that their standard enthalpy ( H^ ) and standard entropy ( S^ ) changes are independent of temperature: (i) N₂(g) + O₂(g) 2NO(g) (ii) N₂(g) + 3H₂(g) 2NH₃(g) (iii) N₂O₄(g) 2NO₂(g) Let m₁ , m₂ , and m₃ be the slopes of the plots of standard Gibbs free energy change ( G^ ) versus temperature ( T ) for reactions (i), (ii), and (iii) respectively. Which of the fo

Step-by-step solution

The standard Gibbs free energy change is given by the equation: G^ = H^ - T S^ When G^ is plotted against T , the equation represents a straight line ( y = c + mx ) where the slope m = - S^ . The sign of S^ can be predicted from the change in the number of gaseous moles ( n_g ): For reaction (i): n_g = 2 - (1 + 1) = 0 . Thus, S^ 0 , which means m₁ 0 . For reaction (ii): n_g = 2 - (1 + 3) = -2 . The number of gaseous moles decreases, so S^ 0 . For reaction (iii): n_g = 2 - 1 = +1 . The number of gaseous moles increa