Question

Predict the sign of the entropy change, ΔS∘, for each of the reaction displayed.

Ba²⁺ (aq) + SO₄^2- (aq) --> BaSO₄ (s)

2NO₂ (g) --> N₂ (g) + 2O₂ (g)

C₅H₁₂ (g) + 8O₂ (g) --> 5CO₂ (g) + 6H₂O (g)

2NaClO₃ (s) --> 2NaCl (s) + 3O₂ (g)

2Na (s) + Cl₂ (g) --> 2NaCl (s)

CH₃OH (l) --> CH₃OH (g)

Answer 1

If chaos increses, then dS is positive

A)

Ba2+ (aq) + SO42- (aq) --> BaSO4 (s) aquoeus ions (chaotic) form a very ordered state, solid, so this is negative

B)

2NO2 (g) --> N2 (g) + 2O2 (g)

2 mol of gas form = 1+2 = 3 mol of gases, there is an increase in entropy

c)

C5H12 (g) + 8O2 (g) --> 5CO2 (g) + 6H2O (g)

9 mol of gas form 11 mol of gases, therefore increases chaos

d)

2NaClO3 (s) --> 2NaCl (s) + 3O2 (g)

solid ofrms gas, there is chaos increase, therefore entropy increases

e)

2Na (s) + Cl2 (g) --> 2NaCl (s)

there is chaos decrease, since 1 mol of gas form solid

f)

CH3OH (l) --> CH3OH (g)

evaporation is always chaos creation, therefore entorpy is positive