For which of the following processes would S° be expected to be most positive? a) O2(g) + 2H2(g)  2H2O(g) b) H2O(l)  H2O(s) c) NH3(g) + HCl(g)  NH4Cl(g) d) 2NH4NO3(s)  2N2(g) + O2(g) + 4H2O(g) e) N2O4(g)  2NO2(g) 12. Which of the following statements is

Explanation:

a) O₂(g) + 2H₂(g) = 2H₂O

b) H₂O(l) = H₂O(s)

c) NH₃(g) + HCl(g) =  NH₄Cl(g)

d) 2NH₄NO₃(s) =  2N₂(g) + O₂(g) + 4H₂O(g)

e) N₂O₄(g) =  2NO₂(g)

ΔS is positive when there is increase in disorderliness. It happens when there is increase in volume .

Increase is volume is maximus in the following reaction.

d) 2NH₄NO₃(s) =  2N₂(g) + O₂(g) + 4H₂O(g)

in this reaction solid NH₄NO₃ is changed to 7 x 22.4 L of gases so there is maximum increase in volume . Hence maximum increase in entropy . Hence ΔS is most positive .

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