Math Problem Statement

Determine ΔG at 298.15K for the reaction. Is it spontaneous? ΔH = -1141.1 kJ, ΔS = -146.5 J/K for the reaction 2NO(g) + O2(g) → 2NO2(g).

Solution

To solve this problem, we need to calculate the Gibbs free energy change (ΔG) for the reaction at 298.15 K and then determine if the reaction is spontaneous.

Given Information:

  • Temperature (T) = 298.15 K
  • Enthalpy change (ΔH) = -1141.1 kJ
  • Entropy change (ΔS) = -146.5 J/K

Since ΔH is given in kJ and ΔS in J/K, let's convert ΔS to kJ/K for consistency: ΔS=146.5J/K=0.1465kJ/K\Delta S = -146.5 \, \text{J/K} = -0.1465 \, \text{kJ/K}

Step 1: Use the Gibbs Free Energy Equation

The Gibbs free energy change, ΔG, can be calculated using the formula: ΔG=ΔHTΔS\Delta G = \Delta H - T \Delta S

Step 2: Substitute Values

ΔG=1141.1kJ(298.15K)×(0.1465kJ/K)\Delta G = -1141.1 \, \text{kJ} - (298.15 \, \text{K}) \times (-0.1465 \, \text{kJ/K}) ΔG=1141.1kJ+43.674475kJ\Delta G = -1141.1 \, \text{kJ} + 43.674475 \, \text{kJ} ΔG=1097.425525kJ\Delta G = -1097.425525 \, \text{kJ}

Step 3: Interpretation

Since ΔG is negative (-1097.43 kJ), the reaction is spontaneous at 298.15 K.

Final Answer:

  • ΔG = -1097.43 kJ (rounded to two decimal places)
  • Spontaneity: The reaction is spontaneous at 298.15 K.

Would you like further details on any of these steps or have any questions?


Here are five related questions to deepen understanding:

  1. How does the sign of ΔG relate to the spontaneity of a reaction?
  2. Why is it necessary to convert ΔS to kJ/K in this calculation?
  3. How would a positive ΔS impact the spontaneity of a reaction?
  4. What would happen to ΔG if the temperature increased?
  5. How does the enthalpy change (ΔH) affect the spontaneity of a reaction?

Tip: Remember that a negative ΔG indicates a spontaneous reaction, while a positive ΔG indicates non-spontaneity.

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Math Problem Analysis

Mathematical Concepts

Thermodynamics
Gibbs Free Energy
Spontaneity of Reactions

Formulas

ΔG = ΔH - TΔS

Theorems

Gibbs Free Energy and Spontaneity

Suitable Grade Level

College level (Chemistry)