The boiling point of a liquid, including alcohol, is influenced by atmospheric pressure. Boiling occurs when the vapor pressure of a liquid equals the surrounding atmospheric pressure. At sea level, where atmospheric pressure is approximately 101.3 kPa (760 mmHg), alcohol (such as ethanol) has a boiling point of about 78.37 °C (173.07 °F).
As atmospheric pressure decreases, such as at higher altitudes, the boiling point of alcohol also decreases. This is because it requires less heat for the vapor pressure of the liquid to equal the lower atmospheric pressure. Conversely, if atmospheric pressure increases, the boiling point of alcohol would increase, requiring more heat for the vapor pressure to match the higher pressure.
To summarize:
- Lower atmospheric pressure = Lower boiling point of alcohol.
- Higher atmospheric pressure = Higher boiling point of alcohol.
This principle is important to consider in cooking, distillation, and various scientific applications where the boiling point of liquids plays a crucial role.
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