Spontaneous Reaction Video Lessons

Concept

# Problem: For the reaction, Fe2O3 (s) + 3 H2(g) &lt;=&gt; 2 Fe(s) + 3 H2O(g), ΔG° = 53 kJ at 25 °C and  ΔH° = 100 kJ.  Which of the following is completely true about the relationship between  ΔG° and T for this reaction?a. ΔG° = 0 when T &lt; 635 Kb. ΔG° &gt; 0 when T &lt; 635 Kc. ΔG° &lt; 0 when T &lt; 635 Kd. ΔG° &gt; 0 when T &gt; 635 Ke. ΔG° &lt; 0 when T &gt; 635 K

###### FREE Expert Solution

We’re being asked to determine which of the is completely true about the relationship between  ΔG° and T for the reaction below:

Fe2O3 (s) + 3 H2(g) ⇌  2 Fe(s) + 3 H2O(g)

ΔG° = 53 kJ at 25 °C
ΔH° = 100 kJ

The relationships given describe the spontaneity of the reaction at different temperatures. Recall that when ΔH and ΔS are given, we can determine the spontaneity of the reaction based on their signs

We can use the Punnett square shown below:

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###### Problem Details

For the reaction, Fe2O3 (s) + 3 H2(g) <=> 2 Fe(s) + 3 H2O(g), ΔG° = 53 kJ at 25 °C and  ΔH° = 100 kJ.  Which of the following is completely true about the relationship between  ΔG° and T for this reaction?

a. ΔG° = 0 when T < 635 K
b. ΔG° > 0 when T < 635 K
c. ΔG° < 0 when T < 635 K
d. ΔG° > 0 when T > 635 K
e. ΔG° < 0 when T > 635 K