Entropy, Enthalpy, And Free Energy Calculated Solution

Consider freezing of water at -10 C and 1 atm pressure.
What is sign of entropy change? explain.  What is the sign of the enthalpy change?explain.  What is the sign of the free energy change?explain

Answer by: dannimay

First Answer Best Answer

Atm pressure

Consider freezing of water at -10 C and 1 atm pressure.
 

 

H2O (l) H20 (s)

 

What is sign of entropy change? explain.

H2O (l) →H20 (s)… this is a phase change, water is going from a liquid to a solid.

 

 

delta S (change of entropy… randomness or disorder) is negative  (-), decrease in randomness, as you go from reactants to products

 

 

 

  What is the sign of the enthalpy change? explain. 

 H2O (l) H20 (s)
Delta H (change of enthalpy: change of heat) will have a negative (-) value. Freezing is an exothermic reaction.

 

 
 

 

What is the sign of the free energy change? explain

delta G rxn ( the overall net change of the reaction, if it has a negative (-) value it is spontaneous, if it has a positive (+) value it is non spontaneous

The sign of delta H and dealta S of the reaction has a relationship with the sign delta G

So for this particular reaction:

H2O (l) H20 (s)

delta H (-) and deltaS (-)….

When the deltaH sign is

When the delta S sign is

Then delta G sign will be

-

-

Dependent of the temperature….

If it is at low temperature……

-      (spontaneous )

If it is at high temperature

    + ( non- spontaneous)

 

Therefore,  the temperature is low, the delta G will have the (-) sign, spontaneous.

 

 

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