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Chapter 11: Problem 23

When pure methanol is mixed with water, the resulting solution feels warm. Would you expect this solution to be ideal? Explain.

Short Answer

Expert verified
The methanol-water solution is not ideal because it feels warm when mixed, indicating that heat is evolved during the mixing process. This exothermic behavior implies that the solute-solvent interactions between methanol and water are stronger than the pure solute-solute and solvent-solvent interactions, resulting in a non-ideal solution.

Step by step solution

01

Understanding Ideal Solutions

An ideal solution is a solution in which the interactions between the solute and solvent particles are essentially the same as those in the pure solvents. In other words, the solute-solvent interactions are equal to the solute-solute and solvent-solvent interactions. This means that there is no change in enthalpy as a result of mixing the solute and solvent, hence, no heat is evolved or absorbed during the process.
02

Exothermic and Endothermic Solutions

In a non-ideal solution, the solute-solvent interactions are different from the interactions present before mixing. This difference in interactions results in a change in enthalpy. Depending on whether the solute-solvent interactions are stronger or weaker than the solute-solute and solvent-solvent interactions, the solution can be exothermic (heat evolves) or endothermic (heat is absorbed).
03

Methanol-Water Solution

In the given exercise, when methanol is mixed with water, the resulting solution feels warm, which indicates that heat is evolved during mixing. This means that the solute-solvent interactions, in this case between methanol and water, are stronger than the pure solute-solute and solvent-solvent interactions. Therefore, mixing methanol and water results in an exothermic process.
04

Conclusion

Based on the observation that the methanol-water solution feels warm, we can conclude that the solution is not ideal, as energy is released in the form of heat due to the difference in solute-solvent interactions compared to the pure solute and solvent. The solution is exothermic and non-ideal.

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Most popular questions from this chapter

In some regions of the southwest United States, the water is very hard. For example, in Las Cruces, New Mexico, the tap water contains about 560$\mu \mathrm{g}$ of dissolved solids per milliliter. Reverse osmosis units are marketed in this area to soften water. A typical unit exerts a pressure of 8.0 atm and can produce 45 \(\mathrm{L}\) water per day. a. Assuming all of the dissolved solids are \(\mathrm{MgCO}_{3}\) and assuming a temperature of \(27^{\circ} \mathrm{C},\) what total volume of water must be processed to produce 45 L pure water? b. Would the same system work for purifying seawater? (Assume seawater is 0.60\(M \mathrm{NaCl.} )\)

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