Question

• Explain the concept of free energy, discussing how it can be used to determine whether a reaction is spontaneous or non-spontaneous
  • Under which conditions would a reaction be spontaneous regardless of temperature?
  • Under which conditions would a reaction be non-spontaneous regardless of temperature?

Answer 1

• Free energy, called Gibbs free energy (G), is the difference between such a system's enthalpy and its entropy product, and also its absolute temperature. It shows the amount of internal energy needed for a thermodynamic device to perform the work. It is the energy that even in a system it is at standard temperature and pressure, can also be transformed in to the work.

  The Gibbs Free Energy equation is:

  G = H – TS

  Where, Gibbs is free energy, enthalpy is H, temperature is T, and entropy is S.

• This means that they might continue without even an energy input and therefore is spontaneous, indicating that there would be a reaction without additional energy. In comparision, reactions with a positive uncertainty need a non-spontaneous amount of energy to occur. As it is found from the above equation, that both increase in enthalpy and the increase in entropy continue to the overall sign and value of ∆G.If a reaction releases heat (negative [H]) or increases system entropy, such variables are often more negative. But at the other end, whenever a reaction absorbs heat or reduces the system entropy, those factors make ∆G more positive.
• It can be seen, at ∆H and ∆S, we can tell whether a reaction will be spontaneous, non-spontaneous, or spontaneous only at certain temperatures. If a reaction both releases heat and increases entropy, it will always be spontaneous (have a negative ∆G), irrespective of temperature. Likwise, throughout all temperatures, a reaction that both absorbs heat and decreases entropy can be non-spontaneous (positive ∆G).