Science Explains #2: What does Boiling Point really means?

What does Boiling Point really means?

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Believe me or not but most people might probably got it wrong.
When we are asked “what is the boiling point of water?”. We always answer "at 100 degrees Celsius!". And that is correct (at some point).

But what does boiling point really means? (No, it is not just about reaching 100 degrees Celsius). Without further ado! Science Explains:

The boiling point is the temperature at which the vapor pressure of a liquid equals the external pressure surrounding the liquid. Therefore, the boiling point of a liquid depends on atmospheric pressure.

When a liquid, a glass of water as an example, is heated, its vapor pressure increases until it overcomes the pressure of the gas above it, it will then form bubbles of vaporized liquid as it escapes to the surface where it can burst and be released as gas.

Factors That Affect the Boiling Point

Pressure
The major influence of a liquid’s boiling point is its external pressure. In an open system, the external pressure is most likely at 1 atm (Earth's atmospheric pressure at sea level). Atmospheric pressure varies according to altitude in Earth's atmosphere.

The graph below shows the relationship between external Pressure and the Boiling point for water:

As the external pressure increases, the boiling point also increases, suggesting that the variables are directly proportional.

Now, since we all now know that the boiling point of water at 1 atm (atmospheric pressure) is 100 degrees celsius. Can you tell me at what temperature will the water boil considering its atmospheric pressure equal to 2? (No, definitely not 200 degrees Celsius, I will be checking your answers at the comment section below.)

Type of Molecules

The relative strength of intermolecular forces between the atoms or molecules also affects the boiling point of liquids. The stronger the intermolecular forces, the higher the boiling point, since you must disrupt those forces to change its phase.

The purity of the liquid is also an important influence. For example, if water contains impurities (such as salt), it will boil at a higher temperature than pure water.

I HOPE YOU ENJOYED READING

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Image Sources: [1], [2], [3]

References:
https://chemistry.stackexchange.com/questions/180/why-do-different-substances-have-different-boiling-points
https://www.thoughtco.com/definition-of-boiling-point-604390
https://www.thoughtco.com/what-is-the-boiling-point-of-water-607865
https://sciencing.com/factors-affecting-boiling-point-8566896.html