How is Vapor Pressure Related to Boiling Point?

Joseph Hebert
Owner at - HVAC Buster

Joseph is an HVAC technician and a hobbyist blogger. He’s been working as an HVAC technician for almost 13 years, and he started blogging just...Read more

Vapor pressure is the pressure of a gas in equilibrium with its non-vaporized form. The boiling point is the temperature at which the vapor pressure of a liquid equals the external atmospheric pressure. The two are related because, as temperature increases, so does vapor pressure.

When the vapor pressure reaches atmospheric pressure, boiling occurs.

Vapor pressure and boiling point are closely related. The vapor pressure is the pressure at which a liquid boils. The higher the vapor pressure, the higher the boiling point.

When a liquid has a high vapor pressure, it means that more of its molecules are in the gas phase than in the liquid phase. This makes it easier for the molecules to escape from the surface of the liquid and turn into gas.

How Does Vapor Pressure Affect Boiling Point?

Vapor pressure is the pressure of a gas in contact with its non-vapor phase. The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure. This condition is most commonly reached by heating a liquid in an open container, allowing the vapor to escape into the atmosphere.

When the atmospheric pressure is equal to the vapor pressure, bubbles of vapor form in the body of liquid and rise to its surface, where they break and release their contents into the air (evaporation). The relationship between vapor pressure and boiling point can be illustrated using a boiling point diagram. The left side of the diagram shows various liquids at different temperatures; on the right side is a graph showing how each substance’s vaporpressure changes with temperature.

The lines on this graph are called saturation curves. As can be seen from inspection of both halves of this figure, there are two main points to note about saturation curves: first, that they all have roughly similar shapes; second, that each curve has a unique intersection with the temperature axis (i.e., each substance has its own characteristic boiling point). The shapes of saturation curves are determined by intermolecular forces, which are attractive forces between molecules.

The strength of these attractions determines how much energy is required to break them apart (the enthalpyof vaporization), and hence how much heat must be added during boiling to achieve saturated conditions. For example, water has strong intermolecular attractions because it forms hydrogen bonds between molecules; as a result, water’s saturation curve lies well below those for substances such as ethanol or mercury, which have weaker attractions.

Why are Vapor Pressure And Boiling Point Inversely Related?

As you know, when a substance is heated, it will eventually reach its boiling point – the temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure. Once this happens, the liquid will begin to boil and turn into a gas. But why is it that the vapor pressure and boiling point are inversely related?

Well, it all has to do with intermolecular forces. When molecules are close together (like in a liquid), they are attracted to each other by these forces. The stronger the force, the harder it is for the molecules to break apart and become a gas.

So, substances with strong intermolecular forces have high boiling points because it takes a lot of energy to overcome these attractive forces. Conversely, substances with weaker intermolecular forces have lower boiling points because not as much energy is required to break apart the molecules and turn them into a gas. This is why vapor pressure and boiling point are inversely related – because as one goes up, the other goes down.

Does Higher Vapor Pressure Increase Boiling Point?

Yes, higher vapor pressure does indeed increase boiling point. This is due to the fact that when the vapor pressure is increased, the molecules of the liquid are able to escape from the surface of the liquid more readily. This means that it takes more energy to keep the liquid at its boiling point, and thus the boiling point is raised.

What is the Relationship between Vapor Pressure And Boiling Point Quizlet?

The relationship between vapor pressure and boiling point is a physical phenomenon that occurs when a liquid is heated. When a liquid is heated, the molecules of the liquid begin to vibrate more rapidly. The faster the molecules move, the more energy they have.

Eventually, the molecules have enough energy to overcome the forces holding them together in the liquid state, and they escape into the gas phase. This process is called evaporation. As evaporation occurs, the vapor pressure of the liquid increases.

The vapor pressure is a measure of how much of a substance is present in the gas phase compared to theliquid phase. When the vapor pressure reaches atmospheric pressure (the pressure exerted bythe weight of air), then boiling occurs. The boiling point is thus directly related to vaporpressure—the higher the vapor pressure, the higher the boiling point will be.

This relationshipis why water boils at 100°C (212°F) at sea level but only 90°C (194°F) at high altitudeswhere there is less atmospheric pressure.

Conclusion

Vapor pressure is the pressure of a gas in equilibrium with its non-gaseous form. When a liquid is heated, the molecules gain kinetic energy and start to move faster. At the boiling point, the vapor pressure of the liquid is equal to the atmospheric pressure.

The liquid then boils and turns into a gas. The boiling point of a liquid is determined by its vapor pressure. The higher the vapor pressure, the higher the boiling point.

Vapor pressure is affected by temperature, so as temperatures increase, so does vapor pressure. This relationship between vapor pressure and temperature is called “the Clausius-Clapeyron equation”.

Joseph is an HVAC technician and a hobbyist blogger. He’s been working as an HVAC technician for almost 13 years, and he started blogging just a couple of years ago. Joseph loves to talk about HVAC devices, their uses, maintenance, installation, fixing, and different problems people face with their HVAC devices. He created Hvacbuster to share his knowledge and decade of experiences with people who don’t have any prior knowledge about these devices.