Explain the temperature change upon mixing ethanol and water.

Answer 1

When ethanol and water are mixed, there is a temperature change that occurs. This is due to the interactions between the molecules of ethanol and water. Ethanol has a polar hydroxyl group (OH) in its molecule, which can form hydrogen bonds with water molecules.

As ethanol and water are mixed, new hydrogen bonds form between ethanol and water molecules. This process releases energy in the form of heat, causing the temperature of the mixture to rise. The creation of these new hydrogen bonds is an exothermic process, meaning it gives off heat.

At the same time, the pre-existing hydrogen bonds between water molecules and ethanol molecules are broken, which requires energy. This is an endothermic process, meaning it absorbs heat.

However, the overall mixing process is exothermic because the formation of new hydrogen bonds between ethanol and water molecules releases more energy than is needed to break the initial hydrogen bonds. As a result, the temperature of the mixture increases, and the mixture becomes slightly warmer than the initial temperatures of the separate liquids.