Why does the temperature of boiling water remain the same as long as the heating and boiling continue?
A certain amount of heat must be added to water to change it from liquid water to water vapor (steam). After water has been heated from, say room temperature, to 100, all of that energy is being absorbed by the liquid. At 100, more heat is added and the liquid changes to steam. So the temperature will stay at 100 (that is to say the water will continue boiling) until all of it has been changed to the vapor state. Forming steam removes heat from the liquid water and that keeps the liquid at 100 C. After all of the water has been converted to steam there is no more removing heat by steam formation, then the temperature can rise higher.
The temperature of boiling water remains constant at its boiling point as long as the heating and boiling continue due to a phase change known as "latent heat of vaporization."
To understand why this happens, we need to first understand the concept of heat transfer. Heat is a form of energy that can be transferred from one object to another. When we add heat to a substance, its temperature generally increases. However, during a phase change, such as boiling, the heat energy is used to overcome the forces of attraction between molecules rather than increasing the temperature of the substance.
When water is heated beyond its boiling point, the heat energy breaks the bonds holding the water molecules together, turning the liquid into vapor or steam. At this point, the energy absorbed is called the latent heat of vaporization. So although heat is still being added to the boiling water, it is being used solely to turn the liquid water into gaseous water vapor, without increasing its temperature.
The boiling point of water at sea level is 100 degrees Celsius or 212 degrees Fahrenheit. When the water reaches this temperature, any additional heat added to the system is absorbed as latent heat and used to convert liquid water into steam. As long as the water is boiling, the temperature will remain constant at the boiling point.
It's important to note that variations in atmospheric pressure can alter the boiling point of water. The boiling point decreases at higher altitudes because the lower atmospheric pressure reduces the forces of attraction between water molecules, allowing them to acquire sufficient energy to escape into the gas phase at lower temperatures.
In summary, the temperature of boiling water remains constant as long as the heating and boiling continue because the added heat is absorbed as latent heat of vaporization, which is used to convert the liquid water into steam rather than increasing the temperature.