Boiling Points: Definition and Example

It doesn’t matter what temperature it is, a liquid will partially evaporate into space above it until the pressure imposed by the vapour reaches a certain value known as the vapour pressure of the fluid at that temperature. In proportion to the increase in heat, the increase in vapour pressure increases; when the temperature reaches the boiling point, bubbles of vapour occur inside the liquid and come to the surface. In relation to the pressure exerted to the liquid, its boiling point is determined; the normal boiling point is defined as the temperature where the vapour pressure equals the standard sea-level atmospheric pressure (760 mm [29.92 inches] of mercury). A thermometer reading of 100 degrees Celsius (212 degrees Fahrenheit) indicates that water is boiling. Lower temperatures at greater elevations are required to reach boiling point.

Boiling Point

A liquid’s boiling point is a temperature where the pressure applied by its surroundings on the liquid is equal to the pressure applied by the liquid’s vapour; at this temperature, the increase of heat causes the liquid to transition into its vapour phase without increasing the temperature.Liquid boiling points are determined by the pressure exerted on it from all sides. It also has a greater boiling point whenever the liquid is subjected to excessive pressure instead of when subjected to normal air pressure. For such a specific pressure, the boiling temperature of various liquids varies.Because heat is continually being delivered to the environmental system, once all of the particles in the liquid state have really been converted into gaseous state, temperature starts to rise once more. The kinetic energy of a particle rises according to the rise in temperature.

Example of Boiling point

After water heats up until it turns into steam, this is a perfect demonstration of boiling. It takes 212 degrees Fahrenheit (100 degrees Celsius) for pure water to boil at sea level. Bubbles in water include water vapour, often known as steam, that is present in the water’s vapour state. There’s less pressure pressing on the bubbles as it moves near the surface, the bubbles grow in size when it becomes closer to the surface.

Vapour

Vaporizable materials are those that exist in the gaseous phase but that would ordinarily exist as liquid or solid below a specific set of conditions. With the pressure applied, vapour can be converted into a liquid or solid as long as the temperature is under a particular point, the crucial temperature; it differs for every element. 

When water vapour (gaseous stage water) is present at room temperature as well as one atmospheric pressure, it is considered to be the most prevalent type of vapour. Avoid conflating vapour with other terms such as dust, which is a perfect dispersion of solid particles, or mist, which is a tiny dispersion of water vapour. Gas is an excellent synonym (alternative word) for vapour.In the scientific community, this is known as the term “vaporisation.” It is defined as the transformation of a substance from a solid or liquid state to that of a gas state. 

Equals atmospheric pressure

The normal boiling point of a liquid, also known as the atmospheric pressure boiling point of a liquid, is perhaps temperature at where the vapour pressure equals the surrounding prevailing atmospheric pressure. As the temperature of the substance rises incrementally, the vapour pressure builds up to the point where it may surpass atmospheric pressure and raise the liquid to form vapour bubbles within the bulk of the material. When bubbles form deeper in the liquid, the temperature must be higher due to the increased fluid pressure, which increases above the air pressure as the depth of the bubbles increases. The increased temperature necessary to initiate bubble production at shallow depths is more significant at shallow depths. An overpressure is created by surface tension on the bubble wall, which is particularly noticeable in the extremely small initial bubbles.

Gas phase

While the state shift between a liquid and a gas is distinct, it has several characteristics with the change of state between a solid and a liquid. When a liquid reaches a specific temperature, the particles within it have enough energy to transform into gas. The procedure by which a liquid turns into a gas is known as boiling or evaporation, whereas the process by which a gas turns into a liquid is known as condensation. Although the liquid/gas conversion process is less noticeable than the solid/liquid conversion process, it is significantly influenced by the external pressure on the liquid due to the fact that gases are extremely sensitive to changes in pressure. As a result, the temperatures where a liquid turns into a gas, known as the boiling point, might vary depending on the surrounding pressure. Because of this, we define a liquid’s normal boiling point as the temperature where it transitions from a liquid to a gas whenever the ambient pressure is approximately one atmosphere, or 760 torr. The boiling point is assumed to be for 1 atmosphere of pressure unless otherwise specified.

Conclusion

The boiling point of a liquid is the temperature where the vapour pressure of the liquid matches the pressure of the surrounding environment. This means that air pressure has an effect on the boiling point of liquids. Because of the reduction in external pressure, the boiling point of the liquid decreases.For such a specific pressure, the boiling temperature of various liquids varies.When water vapour is present at room temperature as well as one atmospheric pressure, it is considered to be the most prevalent type of vapour.An overpressure is created by surface tension on the bubble wall, which is particularly noticeable in the extremely small initial bubbles.