Which factor primarily affects the boiling point of water?

The boiling point of water is primarily affected by atmospheric pressure. When atmospheric pressure decreases, as it does at higher altitudes, the boiling point of water also decreases. Conversely, at higher pressures, such as in a pressure cooker, water can boil at temperatures above 100 degrees Celsius. This relationship between pressure and boiling point is a fundamental principle in thermodynamics and is critical for various applications, including cooking and industrial processes.

Temperature, while related, is a result of energy input to the water rather than a direct factor affecting its boiling point under normal atmospheric conditions. Humidity levels concern the water vapor content in the air and influence perceived moisture but do not have a significant direct effect on boiling point. Salt concentration can alter the boiling point of water slightly through a phenomenon known as boiling point elevation, but this effect is much less significant than that of atmospheric pressure.