Question

When pure methanol is mixed with water, the solution gets warmer to the touch. Would you expect this solution to be ideal? Explain.

Short answer

When methanol is added to the water, there is a formation of intramolecular hydrogen bonds which is an exothermic process and releases heat, this is the reason behind the increase in the temperature of the solution.

Step-by-step solution

Introduction

Water is a polar molecule that forms strong intermolecular hydrogen bonds. Similarly, methanol also possesses hydrogen and forms an intermolecular hydrogen bond when combined with its own molecule or with another molecule, but the strength of the hydrogen bond is different in both molecules.

Explanation

When methanol and water are mixed with each other they dissolve readily because some of the intramolecular hydrogen bonds are broken i.e., bonds within the same molecule, and simultaneously some of the intermolecular hydrogen bonds forms i.e., between methanol and water. The breaking of intramolecular bonds is an endothermic process and no heat is evolved whereas when a new hydrogen bond is formed, it is an exothermic process and thus heat evolves. And this is the reason that solution gets warmer.