How to Measure Vapor Pressure?

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

There are a few different ways that you can measure vapor pressure. The most common method is to use a mercury manometer, which is basically just a glass tube with mercury in it. Another option is to use an electronic vapor pressure sensor, which is more accurate but also more expensive.

Finally, you can also calculate vapor pressure using the Ideal Gas Law, which is less accurate but still useful in some situations.

  • There are a few different ways that vapor pressure can be measured
  • One common method is the use of a manometer, which is simply a tube filled with mercury or another liquid
  • The other end of the tube is attached to the substance whose vapor pressure is being measured
  • As the temperature of the substance increases, the vapor pressure also increases and causes the mercury level in the tube to rise
  • By measuring the height of the mercury column, the vapor pressure can be determined
  • Another common method for measuring vapor pressure is through the use of an electronic sensor
  • This type of sensor uses a small amount of power to measure the change in electrical resistance that occurs as vapors build up on its surface
  • As more vapors condense onto the sensor, its resistance decreases
  • By monitoring this change in resistance, vapor pressure can be calculated

How to Calculate Vapor Pressure from Boiling Point

Vapor pressure is the pressure of a gas in equilibrium with its non-vaporized state. The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the atmospheric pressure. The boiling point can be calculated from the vapor pressure using Antoine’s equation:

log10(P) = A – (B / (T + C)) where P is the vapor pressure in mmHg, T is the temperature in degrees Celsius, and A, B, and C are Antoine’s coefficients for a given substance. To calculate the vapor pressure from boiling point, first convert the boiling point to degrees Celsius if necessary.

Then plug the values into Antoine’s equation and solve for P. For example, to calculate the vapor pressure of water at 100°C, we would use: log10(P) = 8.07131 – (1730.63 / (100 + 233.15)) = 2.471679 – 7.510664 = -5.03901

Calculate Vapor Pressure Calculator

If you’re a chemist or working in a lab, you know that calculating vapor pressure is an important part of your work. But what is vapor pressure, and how do you calculate it? Vapor pressure is the pressure of a gas above a liquid.

The higher the vapor pressure, the more likely the liquid will evaporate. So when you’re working with volatile chemicals, it’s important to know the vapor pressures of those chemicals. There are several different ways to calculate vapor pressure, but one of the easiest is to use the Antoine Equation.

This equation takes into account temperature and atmospheric pressure, two factors that can affect vapor pressure. To use the Antoine Equation, you need three constants: A, B, and C. These constants are specific to each chemical and can be found in tables or online calculators. Once you have these constants, plug them into the equation:

log10(P) = A – (B/(T+C)) where P is vapor pressure (in millimeters of mercury), T is temperature (in degrees Celsius), A is the constant A, B is the constant B, and C is the constant C. log10 stands for “log base 10.”

This just means that we’re using 10 as our exponent instead of 2 or some other number. You can use any calculator to perform this calculation, but many chemists prefer to use Excel because it has a built-in function for logarithms (LOG10). Once you have your answer, convert it to atmospheres by dividing by 760 mmHg (the standard atmosphericpressure).

How to Calculate Vapor Pressure at a Given Temperature

Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. All liquids and solids have a characteristic vapor pressure that depends on the material’s temperature. The higher the temperature, the higher the vapor pressure.

You can calculate the vapor pressure of a liquid at a given temperature using the Clausius-Clapeyron equation: ln(P1/P2) = (ΔHvap/R)(1/T1 – 1/T2) where P1 is the vapor pressure of the liquid at temperature T1, P2 is the vapor pressure of the liquid at temperature T2, ΔHvap is the heat of vaporization for the liquid, R is the universal gas constant, and T1 and T2 are absolute temperatures.

To use this equation, you need to know ΔHvap and R for your material. These values can be found in tables or online databases. Once you have these values, plug them into the equation along with your chosen temperatures (in Kelvin), and solve for P1 or P2.

How to Calculate Vapor Pressure of Water

When water is heated, the molecules gain energy and begin to move faster. Eventually, they move so fast that they break free of the attractions holding them together in liquid form. When this happens, they form a vapor or gas.

The temperature at which this occurs is called the boiling point. The vapor pressure of water is the pressure exerted by the water vapor present above a liquid surface. It is usually expressed in terms of the saturated vapor pressure, which is the vapor pressure when water is in equilibrium with its own vapor (i.e., when it is boiling).

The formula for calculating saturated vapor pressure is: P = 760mm Hg * e^(-5.593*10^-2*T) where T is temperature in degrees Celsius.

For example, at 100°C, P = 2386 mm Hg. This means that if you have a container of water at 100°C and an identical container with nothing but air above it (at atmospheric pressure), the water will exert a force on the walls of its container equal to 2386 mm Hg.

Which Instrument is Used to Measure Vapour Pressure?

Instrument used to measure Vapour pressure The most common instrument used to measure vapour pressure is the manometer. This is a simple device that consists of a tube filled with liquid, usually mercury, with a scale attached.

The other end of the tube is open to the atmosphere. When the atmospheric pressure changes, the level of liquid in the tube also changes and this can be read off the scale. Another type of instrument that can be used to measure vapour pressure is an electronic sensor known as a capacitive manometer.

This device uses an electric field to sense changes in atmospheric pressure and so can be more accurate than a traditional mercury manometer.

What is Vapor Pressure And How is It Measured?

Vapor pressure is the pressure of a gas in equilibrium with its non-gaseous form. The higher the vapor pressure of a substance, the more volatile it is. Vapor pressure is measured in units of mmHg or millimeters of mercury.

To measure vapor pressure, one places a sample of the substance in an enclosed container with a mercury manometer connected to it. By reading the level of mercury in the manometer, one can determine the vapor pressure exerted by the substance on the walls of the container.

How Do You Calculate Vapor Pressure from Boiling Point?

To calculate vapor pressure from boiling point, you must first determine the atmospheric pressure. This can be done using a barometer. Once the atmospheric pressure is known, the boiling point can be determined using a thermometer.

The vapor pressure can then be calculated using the Ideal Gas Law: PV = nRT Where P is the atmospheric pressure, V is the volume of the container, n is the number of moles of gas, R is the universal gas constant, and T is the temperature in Kelvin.

How Does a Barometer Measure Vapor Pressure?

A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather. Many modern barometers use an aneroid capsule that expands or contracts with changes in air pressure, but mercury barometers are also still used.

How does a barometer measure vapor pressure? When air rises, it expand and the mercury is pushed up the tube. As air cools and falls, the mercury is drawn back down the tube.

The difference between these two readings gives you the amount of atmospheric pressure for that particular day and time.


To measure vapor pressure, you will need: -A clean, dry glass container with a tight-fitting lid -A kitchen thermometer

-Table salt -Water -Ice cubes

First, fill the container with ice cubes and water so that the water level is just below the rim of the container. Add a pinch of salt to the water and stir until it is dissolved. Place the lid on the container tightly and insert the thermometer through the lid.

Wait until all of the ice has melted and record the temperature. This is your starting pressure. Next, place your sample on top of the ice water in the container and wait for it to reach equilibrium.

At equilibrium, there will be no net transfer of molecules between your sample and the surrounding atmosphere. Record the temperature once equilibrium has been reached. The difference between your starting pressure and ending pressure is your vapor pressure.

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.

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