Boiling point of a substance is the exact temperature reading at which the specific substance changes its liquid state to vapour or gaseous state. In other words, Boiling point is the temperature, in which the liquid and vapour state of a substance remain in equilibrium. Every element or substance has a standard Boiling point, based on the material makeup or component particles. This particular boiling temperature for a substance fluctuates with respect to surrounding environmental conditions such as altitude and atmospheric pressure.
All of us are aware about water Boiling point or water turning to steam. In fact, we boil water every day for some or the other purpose, such as making beverages (tea, coffee, etc.), cooking foods, sterilizing medical equipments and many other instances. However, it is to be noted that the Boiling point of water changes with several factors. So, what is the temperature of boiling water? More information regarding the Boiling point of water and the phenomenon behind boiling coming up in the following paragraphs.
Boiling point is defined as the temperature when the vapour pressure of the substance or liquid is similar to the external pressure or atmospheric pressure surrounding the solution. A further increase in temperature from this Boiling point is taken up by the liquid as latent heat of vaporization, which helps in changing the liquid to gaseous state. This way, water heated at a temperature higher than Boiling point is evaporated as steam. You can refer to the following information to know about water Boiling point in different scales:
- Water Boiling point in Celsius - The Boiling point of water is 100 degrees Celsius at 1 atmosphere. The bubbles formed on the sides of vessel at the time of heating water are nothing but the air trapped in water.
- Water Boiling point in Fahrenheit - The Boiling point of water in Fahrenheit is 212 degrees, when measured at 1 atmosphere. It is observed that every 152 metres elevation in altitude corresponds to 1 degree drop in water Boiling point.
The change in water Boiling point with reference to certain aspects is an interesting subject for science fair projects. When we say Boiling point of water or any other substance, it is understandable that the pressure is maintained at a standard atmospheric pressure. In general, the Boiling point of a solution changes with respect to the pressure surrounding the liquid at that particular time. And this change in boiling temperature is directly proportional to pressure.
Speaking about water Boiling point, it is lower at higher altitudes where the atmospheric pressure is low, as compared to the standard Boiling point measured at 1 atmosphere or 760 mm of mercury. This explains the phenomenon of distilling water at a much lowered temperature in laboratories. In such cases, the pressure is maintained minimum (e.g. in vacuum flasks), which ultimately makes water boil at a temperature lower than the standard Boiling point. Thus, pressure is usually mentioned while writing the Boiling point of a specific liquid.
Another factor that elevates water Boiling point is the presence of solute or other compounds. This is known as Boiling point elevation, a basic colligative property in chemistry. To be more precise, the Boiling point of water in pure form is lower than salted water or any other solution prepared by adding compounds. You can experiment this on your own at home or in laboratory. Likewise, Boiling point of a pure solvent is lower than its solution.
If you compare Boiling point of water with hydrogen sulphide or other hydrogen compounds, you will find it relatively high. This high temperature reading is due to strong hydrogen bonds that held the water molecules tightly. With this information on water Boiling point, I hope you have understood the phenomenon that takes place at the time of boiling water and the factors that affect it.