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For the reaction

2 C4H10 (g) + 13 O2 (g) ® 8 CO2 (g) + 10 H2O (g)

DH° is -125 kJ/mol and DS° is +253 J/K · mol. This reaction is ________.
Group of answer choices

spontaneous at all temperatures
spontaneous only at high temperature
spontaneous only at low temperature
nonspontaneous at all temperatures
unable to determine without more information

User Yejin
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1 Answer

4 votes

Answer:

The reaction is spontaneous only at high temperatures and nonspontaneous at low temperatures. So the best answer would be spontaneous only at high temperature.

Step-by-step explanation:

The spontaneity of a reaction can be determined by comparing the changes in enthalpy (DH°) and entropy (DS°).

In this reaction, DH° is -125 kJ/mol, indicating an exothermic reaction where heat is released. The negative sign indicates that the reaction is favorable in terms of enthalpy.

DS° is +253 J/K · mol, indicating an increase in disorder or randomness. The positive value of DS° suggests that the products have greater entropy than the reactants.

To determine the spontaneity of the reaction, we need to consider both DH° and DS°.

If a reaction is spontaneous, it means that it will occur without any external influence. In this case, a spontaneous reaction would have a negative value for Gibbs free energy change (DG°). The equation for calculating DG° is:

DG° = DH° - TDS°

where T is the temperature in Kelvin.

Since DH° is negative and DS° is positive, the sign of DG° will depend on the temperature.

At high temperatures, the TDS° term dominates, making the reaction spontaneous. This is because the positive entropy change overcomes the negative enthalpy change, resulting in a negative DG°.

At low temperatures, the DH° term dominates, making the reaction nonspontaneous. This is because the negative enthalpy change overcomes the positive entropy change, resulting in a positive DG°.

Therefore, the reaction is spontaneous only at high temperatures and nonspontaneous at low temperatures.

User Jollyra
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