Which of the following reactions results in a decrease in entropy?

CaCO3 (s) CaO (s) + CO2 (g)
N2O4 (g) 2NO2 (g)
CaO (s) + SO3 (g) CaSO4 (s) 2NH3 (g) N2 (g) + 3H2 (g)

@nechirwan

Question

Which of the following reactions results in a decrease in entropy?

 CaCO3 (s)  CaO (s) + CO2 (g) 
N2O4 (g)  2NO2 (g) 
 CaO (s) + SO3 (g)  CaSO4 (s) 2NH3 (g)  N2 (g) + 3H2 (g)

@nechirwan

anonymous · Answer

CaCO3 (s)  CaO (s) + CO2 (g)
 N2O4 (g)  2NO2 (g) 
 CaO (s) + SO3 (g)  CaSO4 (s)
 2NH3 (g)  N2 (g) + 3H2 (g)

nechirwan · Answer

CaO + SO3 yields CaSO4. This reaction results in a decrease in entropy because      you get solid calcium sulphate, which is more ordered as compared to other gaseous products.