Enthalpy, Entropy, and Free Energy

Consider the reaction 2SO2(g) + O2(g) mc021-1.jpg 2SO3(g). Substance. ΔHf (kJ/mol). S (J/(mol K)) SO3(g). -396. 130.58 SO2(g). -297. 191.50 O2(g). 0. 205.00 What is the mc021-4.jpgGrxn of this reaction, and would it be spontaneous or nonspontaneous at 300.0 K? Use mc021-5.jpgG = mc021-6.jpgH - Tmc021-7.jpgS. -296 kJ/mol, spontaneous -296 kJ/mol, nonspontaneous -100 kJ/mol, spontaneous -100 kJ/mol, nonspontaneous

-100 kJ/mol, spontaneous

What is ΔGrxn for the equation below? NaOH(aq) + HCl(aq) mc025-2.jpg H2O(l) + NaCl(aq) ΔHrxn = -56.13 kJ ΔSrxn = 87.1 J/K T = 303 K Use ΔG = ΔH - TΔS. -82.5 kJ -29.7 kJ 26,500 kJ 27,000 kJ

-82.5 kJ

Calculate ΔGrxn for this equation, rounding your answer to the nearest whole number. 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g) ΔGf,NH3 = −16.66 kJ/mol ΔGf,H2O = −228.57 kJ/mol ΔGf,NO = 86.71 kJ/mol ΔGrxn = ? kJ Is this reaction spontaneous or nonspontaneous?

-958 kJ spontaneous

Which statement describes spontaneous processes? proceed without continuous external influence and have an overall negative free energy change proceed without continuous external influence and have an overall positive free energy change proceed with continuous external influence and have an overall negative free energy change proceed with continuous external influence and have an overall positive free energy change

proceed without continuous external influence and have an overall negative free energy change

Examine the following processes. i.Glucose breaks down in our bodies to provide energy. ii.A lump of sugar dissolves in a cup of coffee. iii.A candle burns. iv.Ice cream melts on a hot day. v.Food is refrigerated in a refrigerator. vi.A drop of food coloring spreads in a glass of water. Which arrangement correctly categorizes the above processes into either spontaneous or nonspontaneous processes? spontaneous: i nonspontaneous: ii, iii, iv, v, vi spontaneous: i, ii, v nonspontaneous: iii, iv, vi spontaneous: i, ii, iii, iv, vi nonspontaneous: v spontaneous: i, v nonspontaneous: ii, iii, iv, vi

spontaneous: i, ii, iii, iv, vi nonspontaneous: v

Trevor dissolves sodium hydroxide pellets in a beaker of water at room temperature, and notes that the beaker becomes warm. Which correctly designates the signs of ΔH, ΔS, and ΔG for this process? ΔH > 0, ΔS > 0, and ΔG < 0 ΔH < 0, ΔS > 0, and ΔG < 0 ΔH > 0, ΔS > 0, and ΔG > 0 ΔH < 0, ΔS < 0, and ΔG > 0

ΔH < 0, ΔS > 0, and ΔG < 0

Marcela dissolves 80.0 g of ammonium nitrate in 50.0 mL of water at room temperature and notes that the temperature of the solution decreases by 5.0°C. Which correctly designates the signs of ΔH, ΔS, and ΔG for this reaction? ΔH > 0, ΔS > 0, and ΔG < 0 ΔH < 0, ΔS > 0, and ΔG < 0 ΔH > 0, ΔS > 0, and ΔG > 0 ΔH < 0, ΔS < 0, and ΔG > 0

ΔH > 0, ΔS > 0, and ΔG < 0

Calculate ΔGrxn for this equation, rounding your answer to the nearest whole number. CaCO3(s) → CaO(s) + CO2(g) ΔGf,CaCO3 = −1,128.76 kJ/mol ΔGf,CaO = −604.17 kJ/mol ΔGf,CO2 = −394.4 kJ/mol ΔGrxn = ? kJ Is this reaction spontaneous or nonspontaneous?

130 kJ nonspontaneous

What is ΔS for the reaction N2(g) +O2(g) → 2NO? Use ΔG = 173.3 kJ at 303.0 K and ΔH = 180.7 kJ. Use ΔG = ΔH - TΔS. 7.4 J/K 7.4 kJ/K 24.42 kJ/K 24.42 J/K

24.42 J/K

The equation CaCO3(s) → CaO(s) + CO2(g) shows the decomposition of calcium carbonate. ΔH = 178.3 kJ/mol, and ΔS = 160.5 J/(mol K). The free energy change for the reaction is 130.5 kJ/mol. Which correctly states the temperature at which the reaction took place and whether the reaction is spontaneous or nonspontaneous? Use ΔG = ΔH - TΔS. 0.30 K, spontaneous 1.92 K, spontaneous 297.8 K, nonspontaneous 1,924 K, nonspontaneous

297.8 K, nonspontaneous

Calculate ΔGrxn for this equation, rounding your answer to the nearest whole number. 2N2(g) + O2(g) → 2N2O(g) ΔHrxn = 163.2 kJ ΔSrxn = −148 k/J T = 298 K ΔGrxn = ? kJ Does the spontaneity of this reaction depend on temperature?

No, it is nonspontaneous at all temperatures.

Calculate Srxn for the equation below. (Round to the nearest whole number.) 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g) SNH3 = 192.8 J/mol K SO2 = 205.0 J/mol K SNO = 188.83 J/mol K SH2O = 210.8 J/mol K Tri Srxn = ?

Tri Srxn = 180 J/K

Calculate TriSrxn for this equation. Round to the nearest whole number. NaOH(aq) + HCl(aq) → H2O(l) + NaCl(aq) SNaOH = 49.8 J/mol K SHCl = 56.5 J/mol K SH2O = 69.91 J/mol K SNaCl = 115.5 J/mol K Tri Srxn = ? J/K

Tri Srxn = 79 J/K

Consider the spontaneous dissolution of NaCl in water: NaCl(s) → Na+(aq) + Cl −(aq) Predict whether the entropy change for this process is positive or negative and explain your answer. Then, predict whether the free energy change for the process is positive or negative and explain your answer.

Which of these ideas did you include in your answer? When a crystalline solid dissolves, it becomes more disordered. When disorder increases, ΔS is positive. This process probably has a positive ΔS. The process is spontaneous. Spontaneous processes have ΔG < 0; the process has a negative ΔG.

Which process is spontaneous? electrolysis of water into oxygen and hydrogen spreading of a strong fragrance of perfume in a room separation of sodium and chlorine from sodium chloride removal of iron fillings from a mixture by using a magnet

preading of a strong fragrance of perfume in a room

Which process involves a decrease in entropy? burning natural gas water freezing into ice water evaporating on heating dry ice subliming

water freezing into ice