Alcohol and water are both molecules that exist in liquid form at room temperature. However, it is a common observation that alcohol evaporates faster than water. But why is this the case?

The answer lies in the properties of the molecules themselves. Alcohols and water have different molecular structures and different physical properties, which can affect their ability to evaporate.

One key factor that determines the rate of evaporation is the volatility of a substance. Volatility is a measure of a substance’s tendency to evaporate and is related to the strength of the intermolecular forces that hold the molecules together. Substances with weaker intermolecular forces tend to have higher volatility and evaporate more quickly.

Alcohols, such as ethanol and isopropanol, have weaker intermolecular forces than water. This is because alcohols have a hydroxyl group (-OH) attached to their carbon chain, which gives them a polar nature. The polar nature of alcohols allows them to form weaker hydrogen bonds with each other, making them more volatile and more prone to evaporation.

In contrast, water molecules are held together by stronger hydrogen bonds. These hydrogen bonds are formed between the oxygen atom of one water molecule and the hydrogen atoms of other water molecules. The presence of these strong hydrogen bonds makes water less volatile and slower to evaporate.

In conclusion, alcohol evaporates faster than water because it has weaker intermolecular forces and is more volatile. The polar nature of alcohols allows them to form weaker hydrogen bonds, making them more prone to evaporation. In contrast, water has stronger hydrogen bonds and is less volatile. Understanding the properties of these molecules can help to explain their different rates of evaporation.