Question

What affects Gibbs free energy?

Answer 1

Gibbs free energy:-

• Gibbs free energy is the quantity that is basically used to measure the maximum amount of work done in a thermodynamic system when both temperature and pressure are kept constant.
• It is denoted by the symbol ‘G’ and its SI unit is Kilojoules.
• We can also define Gibbs free energy as the maximum amount of work that can be extracted from a closed system.

$∆\mathrm{G}=∆\mathrm{H}-\mathrm{T}∆\mathrm{S}$, where $∆\mathrm{G}=$Gibbs free energy, $∆\mathrm{H}=$change in enthalpy, $∆\mathrm{S}=$change in entropy, $\mathrm{T}=$temperature

Factors affecting Gibbs free energy:-

• When the partial pressure of the reactant gas increases the Gibbs free energy$\left(∆\mathrm{G}\right)$ becomes more negative.
• But when the partial pressure of the product gas increases Gibbs free energy$\left(∆\mathrm{G}\right)$ also becomes more positive.
• When entropy of the system increases that is the reaction releases heat (negative ∆H) the Gibbs free energy$\left(∆\mathrm{G}\right)$ becomes more negative.
• But when the entropy of a system decreases that is the reaction absorbs heat the Gibbs free energy$\left(∆\mathrm{G}\right)$ also becomes more positive.
• From the equation we can see that $\left(∆\mathrm{G}\right)$ depends on T.
• If entropy decreases that is the value of $∆\mathrm{S}=$negative then $\mathrm{T}∆\mathrm{S}$is positive, in this case, if we increase the temperature then the value of the Gibbs free energy increases as well.
• On the other hand if $∆\mathrm{S}=$positive then $\mathrm{T}∆\mathrm{S}$ is negative, in this case, if we increase the temperature then the numerical value of the Gibbs free energy decreases.