why does the temperature of boiling water remain the same as long as the boiling continues?

Because it is a pure compound undergoing a phase change. The constant temperature is a requirement of the Gibbs Phase Rule. It is not obvious why this happens. If the compound is not pure, the tempertaure will rise as it boils off the most volatile components.

Heat is required to change the liquid water to steam (from liquid to gas). As long as there is water in the boiling pot, that process will continue; i.e., water will continue to boil and change from liquid to gas. AFTER all the water has been changed from liquid to gas, THEN (and only then) will the temperature of the steam begin to rise if additional heat is added.

It takes allot of energy to vaporize water. Several BTUs for each change of state because it's changing the molecular structure. Not as much energy required to change temperature in same state.

To get a more detailed understanding of why the temperature of boiling water remains the same as long as boiling continues, let's break it down.

Water boils at a specific temperature, which is 100 degrees Celsius (or 212 degrees Fahrenheit) at standard atmospheric pressure. At this temperature, the molecules of water have enough kinetic energy to overcome the attractive forces between them and transition from the liquid phase to the gaseous phase.

When heat is applied to a pot of water on a stove, the energy is transferred to the water molecules, increasing their kinetic energy. As the temperature rises, the water molecules move faster and faster.

Once the water reaches its boiling point, the extra heat energy is used to break the intermolecular bonds holding the water molecules together, allowing them to escape into the air as steam. This process is called vaporization.

The key concept here is that the energy being added to the system is primarily absorbed by the phase change, rather than causing a significant increase in temperature. During the phase change from liquid to gas, the temperature remains constant because the heat energy is being used to break the intermolecular bonds rather than increasing the kinetic energy of the individual molecules.

This phenomenon is known as the latent heat of vaporization, where a substance absorbs heat at a constant temperature without an increase in kinetic energy. It is this constant temperature during boiling that allows water to stay at 100 degrees Celsius regardless of how long the boiling continues, as long as there is enough water remaining.

It's important to note that this explanation applies specifically to pure water under standard atmospheric pressure. If impurities are present in the water or if the pressure changes, the boiling temperature may be different, and the temperature may not remain constant during boiling.

In summary, the temperature of boiling water remains constant because the absorbed heat is primarily used for the phase change process of converting liquid water into steam, rather than increasing the temperature of the water.