Consider the reactant below at 25°C. Describe the possible product to complete each scenario and justify each response. 4A (1)→ a. a decrease in entropy b. an increase in entropy

1.  Ammonia can be made from the reaction of nitrogen and hydrogen: N2  (g)  +  3 H2 (g)      ⟺        2 NH3 (g) For this reaction, K = 1.6 x 102 and ΔH = -91.8 kcal/mole at 25oC. Is the reaction endothermic or exothermic? Briefly explain. Is there in increase in entropy, a decrease in entropy, or no change in entropy?  Briefly explain. At 25oC, is this reaction product favored or reactant favored? Briefly explain. Do you expect this reaction to be spontaneous at all temperatures?  Briefly explain.

For each of the following reactions determine if the change in entropy was positive or negative:A) Water at 40°C → Water at 25°CB) 2NO2(g) → N2O4(g)C) CH3OH (l) → CH3OH (g)D) PbCl2(s) → PbCl2(aq)

For the following reactions, indicate whether the entropy of the system increases, decreases, or remains nearly the same. a. Al3+(aq) + 3 OH-(aq) → Al(OH)3(s)b. CaCO3(s) → CaO(s) + CO2(g)c. Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s)

2 C4H10 (g)  +  13 O2 (g)   →    8 CO2 (g)  +  10 H2O (g)  a) Without consulting the tables, what sign do you expect for the change in entropy (delta S) for the following reaction?  a. negative b. none of these c. positive d. can not be determined (too close to estimate)   b) Now calculate the change in entropy (delta S) for the following reaction, using the thermodynamic tables   a. 113 J/K b. – 402 J/K c. – 515 J/K d. – 312 J/K e. none of these f. 402 J/K g. 515 J/K h. – 113 J/K i. 312 J/K

The answer may be One or more than One options Choose statements that describe ΔStotal ≥ 0.  When we say that entropy is constant or unchanging, it may have infinitesimally small fluctuations about its average value. You may want to consult the entropy handout from Week 5.   a. During a reversible process, the entropy of any systems is constant.   b. The entropy of an isolated system at equilibrium is constant.   c. As an isolated system relaxes to an equilibrium state its entropy increases.   d. During an irreversible process, the entropy of any system increases.   e. During an irreversible process, the entropy of an isolated system decreases.   f. During a reversible process, the entropy of an isolated system is constant.

The change in entropy, ΔSrxn∘, is related to the change in the number of moles of gas molecules, Δngas. Determine the change in the moles of gas for each of the reactions and decide if the entropy increases, decreases, or has little or no change.   A. C(s)+H2O(g) ⟶ CO(g)+H2(g) Δ?gas= ?   The entropy, ΔSrxn∘, 1) has little or no change 2) increases 3) decreases     B. H2O2(l) ⟶ H2(g)+O2(g) Δ?gas=?     The entropy, ΔSrxn∘, 1) has little or no change 2) increases 3) decreases   C. C2H2(g)+3O2(g) ⟶ 2CO2(g)+2H2O(l) Δ?gas=?    The entropy, ΔSrxn∘, 1) has little or no change 2) increases 3) decreases   D. PCl5(s) ⟶ PCl3(l)+Cl2(g) Δ?gas=?   The entropy, ΔSrxn∘, 1) has little or no change 2) increases 3) decreases

O ENTROPY AND FREE ENERGY Using reaction free energy to predict equilibrium composition D 3/5 Consider the following equilibrium: 2NOC1 (g) - 2NO (g)+ Cl, (g) AG" =41. kJ Now suppose a reaction vessel is filled with 2.68 atm of nitrosyl chloride (NOCI) and 3.74 atm of chlorine (Cl,) at 227. °C. Answer the following questions about this system: rise Under these conditions, will the pressure of Cl, tend to rise or fall? fall Is it possible to reverse this tendency by adding NO? In other words, if you said the pressure of Cl, will tend to rise, can that yes be changed to a tendency to fall by adding NO? Similarly, if you said the no pressure of Cl, will tend to fall, can that be changed to a tendency to rise by adding NO? If you said the tendency can be reversed in the second question, calculate the minimum pressure of NO needed to reverse it. | atm Round your answer to 2 significant digits. II

_____________ is not a Law of Thermodynamics.     "For any spontaneous process, the entropy of the universe increases (ΔSuniv > 0)"     "The entropy of a perfect crystal at absolute zero (0 K) is zero"     "The energy of the universe is constant"     "Matter can not be either created or destroyed"