A chemical reaction occurs at room temperature, which is about (kelvin), What can we say about the change in enthalpy, and the change in entropy, of this reaction, assuming that the change in entropy is positive?
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The Gibbs free energy Δ G of a reaction determines whether a reaction will occur at a given temperature. It can be calculated with the formula,
Δ G = Δ H − T Δ S ,
where T is the temperature in kelvin. When the Gibbs free energy of the reaction is negative, the reaction is said to be exergonic , which basically means that the reaction occurs in the direction it is written in.
Since the given reaction occurs at room temperature, we know that Δ G < 0 and T = 2 9 3 K . Thus,
Δ H − ( 2 9 3 K ) Δ S Δ H Δ S Δ H < 0 < ( 2 9 3 K ) Δ S < 2 9 3 K .
The direction of the less-than sign does not change because we are given that Δ S > 0 . We conclude that Δ S Δ H < 2 9 3 K is the only conclusion we can derive from the given information.
(EDIT: I noticed that the answer choices comparing Δ H and Δ S directly are not appropriate because they have different units and, thus, cannot be compared directly. Can this be fixed somehow?)