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Why does the temperature of water drop when it boils at high altitudes? What's the science behind this?
As altitude rises, the boiling point of water continues to decrease. This phenomenon may be familiar to many people. Many climbers or travelers will notice that when boiling water on high mountains, even if the fire is strong, the water cannot reach the boiling point of 100°C. The reason behind this has everything to do with physics, specifically air pressure.
The relationship between boiling point and air pressure
The boiling point of water is the temperature at which liquid water turns into water vapor. A liquid begins to boil when its vapor pressure reaches the atmospheric pressure of its surroundings. At sea level, the standard air pressure is 101.325 kPa, and the boiling point of water is 100°C. But at high altitudes, the boiling point of water drops due to lower air pressure. For example, at an altitude of approximately 1,905 meters, the boiling point of water drops to 93.4°C.
The boiling point depends on the air pressure of the environment. The lower the air pressure, the lower the boiling point.
Interaction between vapor pressure and boiling point
The vapor pressure of water increases as temperature increases. Therefore, water begins to boil when its vapor pressure reaches ambient air pressure. At high altitudes, the ambient air pressure decreases, which means that water reaches a state equal to its vapor pressure at a lower temperature and begins to boil. This is also why in alpine environments the water does not reach 100°C, although the cooking time may be longer.
Other factors affecting boiling point
In addition to air pressure, the boiling point of water is also affected by other substances. When other substances, such as salt, are dissolved in water, these impurities cause the boiling point of the water to rise, a phenomenon called boiling point elevation. This is because impurities lower the vapor pressure of water, increasing the temperature required to reach boiling at the same pressure.
In salt water, the boiling point of water will be higher than that of pure water.
Cooking challenges at high altitude
People who live at high altitudes often face the challenge of making adjustments when cooking. Since the water in the pot may start to boil at a lower temperature, this means food may not be fully cooked at high altitudes. This is undoubtedly a new challenge for those who are used to cooking at sea level. In this case, you may need to increase the cooking time or use a pressure cooker to increase the air pressure and raise the boiling point of the water.
Continuous research and exploration
With the advancement of science and technology, scientists are paying more and more attention to boiling point research in high-altitude environments. This is not only because of its scientific value, but also because of its importance in practical applications. For example, in expeditions to Mars or other planets, low air pressure will also be a key factor to consider regarding the boiling point of water.
Under different environments, changes in the boiling point of water reveal important laws of nature.
Conclusion
Understanding why the temperature of water drops when it boils at high altitudes will not only improve the quality of plateau dishes, but also allow us to delve deeper into the mysteries of the physical world. With the exploration of this topic, the relevant knowledge has a significant impact on improving the quality of life and advancing science and technology. This makes us think, do these rules of nature also affect other unsolved mysteries?
