The boiling point of water, when measured in degrees Celsius, is conventionally set at 100°C under standard atmospheric pressure, which is 1 atmosphere (atm) or 101.325 kPa at sea level. This temperature is significant in various scientific and practical applications, marking a crucial transition in the physical state of water from liquid to gas. At 100°C, water molecules have gained sufficient energy to overcome intermolecular forces, allowing them to escape into the vapor phase.
The boiling point can vary depending on several factors, including atmospheric pressure and the purity of the water. For instance, at higher altitudes, where atmospheric pressure is lower, water boils at temperatures lower than 100°C. Conversely, in a pressure cooker, where the pressure is increased, water can boil at temperatures significantly higher than 100°C, making it a useful tool for cooking.
Additionally, the concept of boiling point is not exclusive to water; different substances have their own unique boiling points. For example, ethanol boils at approximately 78°C, while iron has a boiling point of about 2862°C. Different compounds exhibit different boiling behaviors based on their molecular characteristics. The boiling points can also change with the presence of solutes; for example, dissolving salt in water will elevate its boiling point, a phenomenon known as boiling point elevation.
Understanding the boiling point of water is fundamental, not only in chemistry and physics but also in culinary arts and industry. It is a crucial factor in cooking methods like steaming or boiling, where the temperature of boiling water can significantly affect cooking times and the final texture of food. It also plays a vital role in various industrial applications including distillation, where precise temperature controls are necessary to separate components based on their boiling points.
In summary, the boiling point of water under standard atmospheric conditions is 100°C, but it is essential to consider other factors like pressure, purity, and presence of solutes that can modify this critical temperature.