Use the table below to answer the questions that follow.
Thermodynamic Quantities for Selected Substances at 298.15 K (25°C)
-The value of ΔS° for the catalytic hydrogenation of acetylene to ethane, is J/K.

Question

Use the table below to answer the questions that follow.
  Thermodynamic Quantities for Selected Substances at 298.15 K (25°C) 
-The value of ΔS° for the catalytic hydrogenation of acetylene to ethane,  is J/K.

Quizplus · Accepted Answer

From the table, we can see that the ΔG° for the reaction is negative (-127.2 kJ/mol). Since the reaction is exothermic, the value of ΔH° will be negative. Also, since the reaction results in a decrease in the number of moles of gas, the value of ΔS° will be negative. 
Using the equation ΔG° = ΔH° - TΔS° and rearranging, we get ΔS° = (-ΔG° + ΔH°)/T. Substituting the values, we get ΔS° = (-(-127.2*10^3) + (-94.8*10^3))/298.15 = -232.5 J/K. Hence, the answer is C.

Use the Table Below to Answer the Questions That Follow