Fact Check: "Water boils at 100°C at sea level."
What We Know
The claim that "water boils at 100°C at sea level" is a well-established scientific fact. Under standard atmospheric pressure at sea level, which is defined as 101.325 kPa (1 atm), water indeed boils at 100°C (or 212°F) (source-2). This boiling point can slightly vary depending on the exact atmospheric pressure, but it is generally accepted as 100°C for practical purposes.
As altitude increases, atmospheric pressure decreases, which in turn lowers the boiling point of water. For example, at an elevation of approximately 1,905 meters (6,250 feet), water boils at about 93.4°C (200.1°F) (source-2). This phenomenon is critical for cooking at high altitudes, where adjustments must be made to cooking times and methods (source-1).
Analysis
The claim is supported by multiple reliable sources, including scientific literature and educational websites. The boiling point of water is a fundamental concept in physics and chemistry, and it is consistently referenced in educational materials. For instance, the Engineering Toolbox explains how the boiling point decreases with altitude due to lower atmospheric pressure, confirming that at sea level, it is indeed 100°C.
Additionally, the NASA source provides a precise definition of the boiling point, noting that it is the temperature at which the vapor pressure of the liquid equals the surrounding pressure. This aligns with the claim that at sea level, water boils at 100°C.
While some sources discuss variations in boiling point due to altitude, they do not contradict the claim; rather, they provide context that reinforces it. For example, the High-altitude cooking article highlights that adjustments are necessary at higher elevations but reiterates the standard boiling point at sea level.
The sources used are credible, with scientific backing and educational intent. They provide a clear understanding of the principles governing boiling points and their dependence on atmospheric pressure.
Conclusion
Verdict: True
The claim that "water boils at 100°C at sea level" is accurate and supported by scientific principles. The boiling point of water is defined under standard atmospheric pressure, and while it changes with altitude, the stated temperature holds true at sea level.
