When water is boiling on a stove, it reaches its boiling point temperature, which is 100 degrees Celsius (212 degrees Fahrenheit) at standard atmospheric pressure. At this temperature, the water molecules have enough energy to overcome the attractive forces between them and transition from the liquid phase to the gaseous phase (water vapor).
When you remove the water from the heat source, several factors contribute to the rapid cessation of boiling:
Loss of Heat Source: The heat source, typically a stove or burner, supplies the energy required to maintain the water at its boiling point temperature. Once you remove the water from the heat source, there is no additional heat being added to sustain boiling.
Loss of Energy Input: Without the continuous input of heat energy, the water starts to lose heat to its surroundings through conduction, convection, and radiation. The rate of heat loss increases as the temperature difference between the water and its surroundings decreases. As a result, the water cools down.
Reduction in Vapor Pressure: When the water is at its boiling point, the vapor pressure (the pressure exerted by the water vapor molecules) is equal to the atmospheric pressure. However, as the water cools down, the vapor pressure decreases. This decrease in vapor pressure means that fewer water molecules have sufficient energy to escape from the liquid phase and form vapor bubbles, resulting in a decrease in boiling activity.
Formation of a Non-Uniform Temperature Gradient: When water is boiling, there is a relatively uniform temperature throughout the liquid due to the constant heat input. However, when the heat source is removed, the temperature gradient within the water becomes less uniform. The upper layers of the water cool down more quickly than the bottom layers, creating a non-uniform temperature distribution. This temperature gradient reduces the likelihood of sustained boiling.
In summary, the water stops boiling almost immediately after removing it from the heat source because it loses the continuous heat supply required to maintain the water at its boiling point temperature. The loss of heat, reduction in vapor pressure, and the formation of a non-uniform temperature gradient all contribute to the cessation of boiling.