Enthelpy/Entropy question. Br2 liquid to 2Br gas

In summary, the chemical reaction of Br2 (l) --> 2Br (g) results in an increase in entropy (S is positive) and a decrease in enthalpy (H is negative). This indicates that the reaction is exothermic and the correct answer is either B or D.
  • #1
Pr0x1mo
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0

Homework Statement


Br2 (l) --> 2Br (g)

the options are:

a. H is positive and S is positive for the reaction
b. H is negative and S is positive for the reaction
c. H is positive and S is negative for the reaction
d. H is negative and S is positive for the reaction
e. G Is positive for all temperatures

Homework Equations



dG= dH - TdS

The Attempt at a Solution



The chemical reaction is going from liquid to gas, therefore the entropy is increasing because the reaction is causing more macrostates due to the greater area of distribution for the gas molecules. The reaction is exothermic, because its giving off heat.

Therefore, Entropy is increasing (S is positive) and since no heat is being absorbed Enthalpy is decreasing (H is negative).

So my answer is B... so here's the dilemma,, B is the same answer as D. I don't know if this was a mistake on the teachers part, or I AM WRONG, and she put the answer there 2x to hint that its not the answer.
 
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  • #2
Why do you say it's exothermic?
 
  • #3


Your solution is correct. As you mentioned, the reaction is exothermic, meaning it releases heat. This leads to a decrease in enthalpy (H is negative). Additionally, the reaction is going from a more ordered state (liquid) to a less ordered state (gas), which results in an increase in entropy (S is positive). Therefore, the correct answer is B. It does seem like there may have been a mistake by the teacher in including the answer twice.
 

1. What is enthalpy/entropy?

Enthalpy and entropy are both thermodynamic properties that describe the energy and disorder of a system, respectively. Enthalpy is the total heat content of a system, while entropy is a measure of the randomness or disorder within a system.

2. What is the process of Br2 liquid to 2Br gas?

The process of Br2 liquid to 2Br gas is known as vaporization or boiling. This occurs when a liquid is heated to its boiling point, causing the molecules to gain enough energy to break away from each other and become a gas.

3. What happens to enthalpy/entropy during this process?

During the process of Br2 liquid to 2Br gas, both enthalpy and entropy increase. Enthalpy increases because energy is added to the system to break the bonds between the molecules. Entropy increases because the molecules become more disordered and spread out in the gas state.

4. How does temperature affect enthalpy/entropy during this process?

Temperature has a direct effect on both enthalpy and entropy during the process of Br2 liquid to 2Br gas. As the temperature increases, so does the enthalpy, as more energy is needed to break the bonds and vaporize the liquid. Entropy also increases with temperature because the molecules move faster and become more disordered.

5. What is the relationship between enthalpy and entropy in this process?

The relationship between enthalpy and entropy in this process is described by the Gibbs free energy equation: ΔG = ΔH - TΔS. This equation shows that as enthalpy increases, so does the overall free energy of the system, but as entropy increases, the free energy decreases. This means that a balance between enthalpy and entropy is necessary for a spontaneous process, such as the vaporization of Br2 liquid to 2Br gas, to occur.

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