Answer to Question #345117 in General Chemistry for bella

Question

Predict whether the entropy change of the system in each of the following is positive or negative.1. O2(g) → 2O(g)2. N2 (g, 10 atm) → N2 (g, 1atm)3. 6CO2(g) + 6H2O(g) → C6H12O6(g) + 6O2(g)4. 2 H2 (g) + O2 (g) → 2 H2O (l)5. NH4Cl (s) → NH3(g) + HCl (g)

Answer 1

Whenever there is an increase in moles in the reaction, then entropy increases. So change in entropy is positive. And whenever the moles on the product side are more than reactants, then entropy decrease

1. O₂(g) → 2O(g)  In this reaction one mole of Oxygen is broken into 2 moles. So moles of product is more than moles of reactant. Therefore change is entropy will be positive in this case.

2. N₂ (g, 10 atm) → N₂ (g, 1atm) positive; the gas expands into a larger volume

3. 6CO₂(g) + 6H₂O(g) → C₆H₁₂O₆(g) + 6O₂(g) In this reaction, the moles on the reactant side is greater than the moles on the product side. So change in entropy will be negative in this case.

4. 2 H₂ (g) + O₂ (g) → 2 H₂O (l) negative

5. NH₄Cl (s) → NH₃(g) + HCl (g) a solid going to the gas. The particles are much more free to move in the gas state that is a positive entropy state.