The heat required to raise the temperature of a substance, in this case, water, to its boiling point (B.P.) is known as the sensible heat or the heat of vaporization. This heat is necessary to increase the kinetic energy of the water molecules, thereby increasing its temperature. The specific heat capacity of water is about 4.18 Joules per gram per degree Celsius (J/g°C), so the amount of heat required to raise the temperature of water can be calculated using the formula:
Q = m * c * ΔT
where Q is the heat energy, m is the mass of water, c is the specific heat capacity of water, and ΔT is the change in temperature.
On the other hand, the heat required to convert water at its boiling point into vapor (steam) is known as the latent heat of vaporization. At the boiling point, the water molecules have enough energy to overcome the intermolecular forces holding them together and transition into the gas phase. During this phase change, the temperature remains constant even though heat is being added. The latent heat of vaporization for water is approximately 40.7 kilojoules per gram (kJ/g).
So, to summarize:
- The heat required to raise water to its boiling point is the sensible heat and depends on the initial temperature and the desired boiling point temperature.
- The heat required to convert water at its boiling point into vapor is the latent heat of vaporization and is independent of temperature, as it only accounts for the phase change.
Both the sensible heat and the latent heat are important in the process of converting liquid water into vapor. The sensible heat raises the temperature to the boiling point, while the latent heat enables the phase change from liquid to vapor.