How does the Enthelpy change tell us about the stability of the product?

In summary, the video being discussed is imprecise in its explanation of enthalpy change and heat exchange. It also does not mention the important concept of heat of formation and incorrectly states that an enthalpy decrease is a criterion for stability of products. The speaker's explanation is not recommended for students due to its low quality.
  • #1
Frigus
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At constant pressure Enthalpy change is equal to heat exchange and we say that "if Enthalpy Change is negative then product formed is stable",
I am not able to make sense of this statement as change in Enthalpy tells us only about heat exchange but internal energy is function of both Work and Heat.
what if work done on the system is more than the heat released?
 
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  • #2
Hemant said:
At constant pressure Enthalpy change is equal to heat exchange and we say that "if Enthalpy Change is negative then product formed is stable",
I am not able to make sense of this statement as change in Enthalpy tells us only about heat exchange but internal energy is function of both Work and Heat.
what if work done on the system is more than the heat released?
Please provide a reference for that statement.
 
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  • #3
Chestermiller said:
Please provide a reference for that statement.

It is also Written it in my notes which are recited by my teacher.
 
  • #4
Hemant said:

It is also Written it in my notes which are recited by my teacher.

With all due respect to your teacher and to this video, they are incorrect.

I have very big problems with this video, because it is extremely imprecise with its explanation (which demands being precise). For example, it does not say that the heat of formation is the amount of heat that has to be added to hold the system at the same temperature as it was initially. Clearly, this is pretty important, but it is omitted. If fact, at some point he even says that the system is adiabatic (which it is not).

Enthalpy decrease is not a criterion for stability of the products relative to the reactants. The correct criterion is a decrease in Gibbs free energy between reactants at the specified temperature and pressure and products at the same temperature and pressure. Even this is a rough rule of thumb.

In my view, this video should never be shown to students because of its low quality. Shame on the speaker.
 
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1. How does the change in enthalpy indicate the stability of a product?

The change in enthalpy, or the heat absorbed or released during a chemical reaction, can provide insight into the stability of a product. A negative change in enthalpy (exothermic reaction) indicates that energy is being released, making the product more stable. On the other hand, a positive change in enthalpy (endothermic reaction) suggests that energy is being absorbed, making the product less stable.

2. Can enthalpy change alone determine the stability of a product?

No, enthalpy change alone cannot determine the stability of a product. Other factors such as entropy, temperature, and pressure also play a role in determining the stability of a product. Enthalpy change is just one piece of the puzzle and should be considered alongside these other factors.

3. How can we use enthalpy change to predict the stability of a product?

By comparing the enthalpy change of a reaction to the enthalpy change of a similar reaction with a known stability, we can make predictions about the stability of the product. For example, if the enthalpy change of a reaction is more exothermic than a similar reaction with a known stable product, we can infer that the product is also likely to be stable.

4. Does the magnitude of enthalpy change affect the stability of a product?

Yes, the magnitude of enthalpy change can affect the stability of a product. A larger enthalpy change, whether positive or negative, indicates a more significant change in energy and can suggest a less stable product. However, other factors such as temperature and pressure should also be considered when determining stability.

5. How does the enthalpy change of a reaction relate to the stability of the product?

The enthalpy change of a reaction is directly related to the stability of the product. A more negative enthalpy change (exothermic reaction) indicates a more stable product, while a more positive enthalpy change (endothermic reaction) suggests a less stable product. This is because a more negative enthalpy change means that energy is being released, making the product more stable, while a more positive enthalpy change means that energy is being absorbed, making the product less stable.

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