What factors determine the feasibility of a chemical reaction?

The factors that determine the feasibility of a chemical reaction are:

  1. The enthalpy change (ΔH).
  2. The entropy change (ΔS).
  3. The temperature (T)

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What is meant by the term Gibbs free energy change (ΔG)?

The Gibbs free energy change (ΔG) represents the overall change in energy during a reaction and is used to assess whether a reaction is thermodynamically feasible.

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What is the equation that links Gibbs free energy change (ΔG), enthalpy change (ΔH), entropy change (ΔS), and temperature (T)?

ΔG =ΔH −TΔS


ΔG = Gibbs free energy change (kJ mol-1).

ΔH = enthalpy change (kJ mol-1).

T = temperature (K)

ΔS = entropy change (J K-1 mol-1).

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How can you use the ΔG value to assess the feasibility of a reaction?

  • If ΔG is less than zero, the reaction is feasible and may occur spontaneously.
  • If ΔG is greater than zero, the reaction is not feasible without an external energy source.

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What is the standard unit of measurement of Gibbs free energy?

J mol-1 or kJ mol-1

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Which letter is conventionally used to represent free energy?

G

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What is the value of ΔG for a reaction at equilibrium?

Zero

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How do you determine the temperature at which a reaction becomes feasible? Explain your answer with an equation.

A reaction is just feasible when ΔG = 0, so you can rearrange and simplify the Gibbs free energy equation as shown below.


T =ΔSΔH​


T = temperature at which a reaction becomes feasible (K).

ΔH = enthalpy change (kJ mol-1).

ΔS = entropy change (J K-1 mol-1).

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What is a feasible reaction?

A feasible reaction is one that occurs without the need for an external energy source.


Feasible reactions have negative ΔG values, indicating that they are energetically favorable.

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