For which of the following reactions is S° > 0. Choose all that apply. NH4I(s) NH3(g) + HI(g) CH4(g) + H2O(g) CO(g) + 3H2(g) 2NH3(g) + 3N2O(g) 4N2(g) + 3H2O(g) 2NH3(g) + 2O2(g) N2O(g) + 3H2O(l) CO(g) + Cl2(g) COCl2(g)

Explanation:

Entropy is the measure of randomness or disorder of a system. If a system moves from  an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

1. : As in this reaction 1 moles of solid reactants are converting to 2 moles of gaseous products. The randomness will increase and hence entropy will also increase. Thus > 0.

2. : As in this reaction 2 moles of gaseous reactants are converting to 4 moles of gaseous products. The randomness will increase and hence entropy will also increase. Thus > 0.

3.  : As in this reaction 5 moles of gaseous reactants are converting to 7 moles of gaseous products. The randomness will increase and hence entropy will also increase. Thus > 0.

4. : As in this reaction 4 moles of gaseous reactants are converting to 4 moles of gaseous products. The randomness will increase and hence entropy will also increase. Thus > 0.

5. : As in this reaction 2 moles of gaseous reactants are converting to 1 mole of gaseous products. The randomness will decrease and hence entropy will also increase. Thus < 0.