Ethanol, also known as ethyl alcohol, is a clear, colorless liquid with a distinct odor, found in alcoholic beverages, hand sanitizers, and as a fuel additive. Understanding its physical properties, like its boiling point, is important for its various applications. When heated, it transforms from a liquid to a gas at a specific temperature.
Understanding Ethanol’s Boiling Point
At standard atmospheric pressure, the boiling point of pure ethanol is approximately 78.37 °C (173.07 °F). The boiling point is the temperature where a liquid’s vapor pressure equals the surrounding atmospheric pressure, causing it to rapidly turn into a gas. For context, water boils at 100 °C (212 °F) under the same conditions.
Ethanol has a lower boiling point than water due to differences in their intermolecular forces. Both ethanol and water molecules engage in hydrogen bonding, a strong intermolecular attraction. However, water molecules form more extensive hydrogen bonds compared to ethanol molecules. Less energy is required to overcome these attractions in ethanol, allowing it to vaporize at a lower temperature.
Factors Affecting Boiling Temperature
Ethanol’s boiling temperature is not fixed and can be influenced by several external factors. One factor is atmospheric pressure. Boiling points depend directly on the external pressure. At higher altitudes, where atmospheric pressure is lower, ethanol will boil below 78.37 °C. Conversely, increased external pressure raises ethanol’s boiling point.
The purity of ethanol also affects its boiling point. When impurities, such as water, are present, the mixture’s boiling point changes. For instance, an ethanol and water mixture will boil at temperatures between their individual boiling points, depending on their ratio. This occurs because other substances change the solution’s overall vapor pressure.
Real-World Relevance and Safety
Knowledge of ethanol’s boiling point applies in various practical scenarios. In processes like alcohol production and purification, distillation relies on the difference in boiling points between ethanol and water to separate them. When an ethanol-water mixture is heated, ethanol vaporizes first due to its lower boiling point. These vapors are then collected and condensed to achieve a higher ethanol concentration.
Ethanol’s boiling point is also important for its use as a fuel and in industrial applications requiring temperature control. Understanding this property is also important for safety. Ethanol is a flammable liquid; its vapors can ignite, especially at or above its boiling point. Proper ventilation and careful handling prevent the accumulation of flammable ethanol vapors, which pose a fire hazard.