Entropy vs. enthelpy in chemical reactions.

In summary, the conversation discusses the use of free energy change (delta G) to determine if a chemical reaction will occur spontaneously. It is determined by the sum of enthalpy change (delta H) and temperature (T) multiplied by entropy change (delta S). The question is posed whether the entropy component can drive a reaction to occur where the outcome is of higher energy, and if such reactions exist and result in stable products. Examples of endothermic spontaneous reactions, such as dissolving kitchen salt in water, are provided.
  • #1
sghan
10
1
Hello,
I am learning about using Free energy change /delta G to determine if a chemical reaction will occur spontaneously. /delta G = /delta H + T*/delta S. Now, enthalpy change can drive a reaction which leads to a decrease in entropy (multiple reactants => single product). My Question: can the entropy component /delta S drive a reaction to occur where the outcome is of higher energy? Do such reactions exist and are the products stable?
 
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  • #2
Hello sghan, :welcome: (there is no 'welcome back' sign yet :smile: )

You are also rlearning about ##\LaTeX## I suppose.

In PF enclose source with ##\#\# ## for in-line ##\TeX## and ##\$\$## for diplsayed equations (bigger, centered) and use a backslash, not a forward slash:

##\#\# ## \Delta G = \Delta H + T \Delta S ##\#\# ## gives ## \Delta G = \Delta H - T \Delta S ## (Note the minus sign)

For examples, google "endothermic spontaneous reactions examples"

Dissolving kitchen salt in water appears to be one example...
 

FAQ: Entropy vs. enthelpy in chemical reactions.

1. What is the difference between entropy and enthalpy in chemical reactions?

Entropy refers to the measure of disorder or randomness in a system, while enthalpy refers to the total energy of a system. In a chemical reaction, entropy and enthalpy both play a role in determining the spontaneity and direction of the reaction.

2. How do entropy and enthalpy affect the spontaneity of a chemical reaction?

In general, a reaction will be spontaneous if the total entropy of the system increases and the total enthalpy decreases. This means that the products have a higher disorder and lower energy than the reactants.

3. Can entropy and enthalpy both be negative in a chemical reaction?

Yes, both entropy and enthalpy can be negative in a reaction. This would indicate that the products have lower disorder and lower energy than the reactants, and the reaction would not be spontaneous.

4. How does temperature affect the role of entropy and enthalpy in chemical reactions?

Increasing the temperature generally increases the amount of disorder in a system, which means that entropy becomes a more important factor in determining the spontaneity of a reaction. However, temperature also affects the overall energy of the system, which can impact the enthalpy of the reaction.

5. Can entropy and enthalpy be used to predict the direction of a chemical reaction?

Yes, the change in entropy and enthalpy can be used to predict the direction of a reaction. A positive change in entropy and a negative change in enthalpy would indicate a spontaneous reaction, while a negative change in entropy and a positive change in enthalpy would indicate a non-spontaneous reaction.

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