Final answer:
The correct expression for the Gibbs energy of mixing for an ideal solution is ΔG = RT(x1 ln(x1) + x2 ln(x2)), which describes how the free energy of the system changes when two pure substances are mixed to form an ideal solution.
Step-by-step explanation:
The Gibbs energy of mixing for two liquids forming an ideal solution is best described by option A: ΔG = RT(x1 ln(x1) + x2 ln(x2)). In this equation, ΔG represents the Gibbs free energy change of mixing, R is the gas constant, T is the absolute temperature in Kelvin, and x1 and x2 are the mole fractions of the two components in the solution, respectively. This equation is derived from the properties of ideal mixtures where the total Gibbs free energy of the system is the sum of the partial molar Gibbs energies of each component, each multiplied by its respective mole fraction.
In general, the Gibbs free energy equation is useful in predicting the spontaneity of a chemical process. If ΔG is negative, the process is spontaneous under the given conditions.