`DeltaG` is net energy available to do useful work and is thus a measure of " free energy".Show mathematically that `DeltaG` is a measure of free energy.Find the unit of `DeltaG`.If a reaction has positive enthalpy change and positive entropy change, under what condition will the reaction be spontaneous?

Explanation

To show mathematically that ΔG is a measure of free energy, we start with the Gibbs free energy equation:

### Step 1: Write the Gibbs Free Energy Equation
The Gibbs free energy (ΔG) is defined by the equation:
\[ \Delta G = \Delta H - T \Delta S \]
where:
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