Which one of the following is incorrect for ideal solution?

Options

A. `Delta H_(mix)=0`
B. `Delta U_(mix)=0`
C. `Delta P=P_(obs.)-P_("calculated by Raoult's law")=0`
D. `Delta G_(mix)=0`

Explanation

To determine which statement is incorrect for an ideal solution, we need to understand the characteristics of ideal solutions. Here’s a step-by-step breakdown of the properties of ideal solutions:

### Step 1: Understand Raoult's Law
An ideal solution is one that follows Raoult's law, which states that the partial vapor pressure of each component in the solution is equal to the vapor pressure of the pure component multiplied by its mole fraction in the solution.

**Hint:** Remember that Raoult's law is fundamental to defining ideal solutions.

### Step 2: Analyze ΔH of Mixing
For ideal solutions, the change in enthalpy (ΔH) upon mixing is zero. This means that the mixing process does not absorb or release heat.

**Hint:** Think about how energy changes during the mixing of substances.

### Step 3: Analyze ΔV of Mixing
The change in volume (ΔV) upon mixing is also zero for ideal solutions, indicating that there is no contraction or expansion in volume when the components are mixed.

**Hint:** Consider how the volumes of the individual components behave when mixed.

### Step 4: Analyze ΔS of Mixing
The change in entropy (ΔS) upon mixing is positive for ideal solutions. This reflects an increase in disorder as the two components mix.

**Hint:** Entropy is related to the randomness of the system; think about how mixing affects this.

### Step 5: Analyze ΔP
For ideal solutions, the difference in vapor pressure (ΔP) between the observed and calculated values is zero, indicating that the solution behaves ideally.

**Hint:** Relate this back to Raoult's law and how it defines ideal behavior.

### Step 6: Analyze ΔG of Mixing
The change in Gibbs free energy (ΔG) for mixing is given by the equation: ΔG = ΔH - TΔS. For ideal solutions, since ΔH is zero and ΔS is positive, ΔG will be less than zero, indicating that the mixing process is spontaneous.

**Hint:** Recall the significance of Gibbs free energy in determining the spontaneity of a process.

### Conclusion
Based on the properties discussed, if any statement contradicts these characteristics, it would be the incorrect one regarding ideal solutions.

In this case, the incorrect statement is related to the Gibbs free energy of mixing, which should be less than zero for ideal solutions.

Thus, the answer to the question is **D**.