PYCNOMETER: CHARACTERISTICS, FUNCTIONS, TYPES - CHEMISTRY - 2025

The p icnómetro is a tool used in laboratories is used to measure the volume or density of an element, either solid or liquid. In turn, it allows to know the temperature of said element.

The pycnometer is of great help, as it is one of the most accurate measuring instruments in the chemical world. For this reason, many scientists prefer to use such an instrument, as it allows them to be more precise in their laboratory experiments.

Pycnometer

There is a methodology that revolves around the pycnometer. It studies the results obtained by said instrument and is known as pycnometry.

Typically, this tool is made of glass and consists of a bowl and a ground cap with a capillary that allows accurate measurement and prevents any spill accidents, which could cause a lot of problems.

It is common to use the pycnometer together with a thermometer, since in this way the temperature of the substance with which you are working can be measured at the same time.

There are many types of pycnometers. However, one of the most used is the gas pycnometer.

This instrument is capable of analyzing solid elements such as ceramics, pharmaceutical ingredients, metallic powders, cement, petroleum coke, among others. In the case of non-porous solids, the pycnometer measures the density of their particles.

Pycnometer function

Pycnometer to find the specific gravity of fine aggregate. Remux / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

The main function of the pycnometer is the measurement of volume of a substance both liquid and solid. There are many ways to achieve this result.

This laboratory instrument is widely used especially in the school area because it is very accurate. Plus, it's very fast (you don't have to wait long for results).

As for the frosted stopper, it is of great help, since it prevents spills and at the same time allows air circulation inside and outside the vessel, which is usually made of glass.

When the pycnometer is used to measure the density of porous solid elements, the element to be measured must first be crushed in order to open all the pores of the substance, so that there are no errors in the results that are desired.

In the case of the measurement of paints a metal pycnometer is used, since this substance in particular requires it.

The American Petroleum Institute (API) strongly recommends the use of the pycnometer in experimental laboratories, due to its precision.

How to use a pycnometer?

The easiest way to use this instrument is to remove the ground stopper and pour the substance (liquid) into the pycnometer vessel. When you put the cap back on, the substance will rise through the inside of the cap to the capillary inside.

Some pycnometers do not have this mechanism, but instead have a long, graduated neck with a marked mark.

In this case, the substance is poured up to the mark and there the volume of it can be measured. To correctly measure the volume distilled water is added.

The entire jar should be filled with distilled water until it spills a little over the top when the cap is inserted. It is important that no air bubbles remain when pouring the distilled water into the pycnometer, as this can cause a radical change in the final results.

Normally, the volume of the water alone must be measured and then the volume of the substance to be analyzed is measured together with the distilled water.

Once with the result of the volume, the final result of how much is the density of the substance or what is its total weight will be obtained.

Characteristics of the pycnometer

The pycnometer is a laboratory tool that exists in many sizes and different materials. Some of them come with a built-in temperature sensor that can compensate for changes in temperature that the substance undergoes during experiments.

On the other hand, some pycnometers have built-in information storage or automatic calibration, which is helpful when working on important data for measuring chemical elements in laboratories.

There is a wide variety of sizes for this instrument and they all vary depending on the substance or item to be measured or weighed.

When dealing with thick or pasty substances (such as paint), a pycnometer is usually used that varies from 25ml to 50ml approximately.

In the case of less viscous substances, pycnometers ranging from 25 ml to 30 ml are used, since their density will be lower. On the other hand, rheological liquids (those that oscillate between liquid and solid) can be measured in pycnometers from 10ml to 25ml.

Pycnometers use the following units to express their results: kg / m ³, g / cm ³. As for their standard, they are governed by ASTM D-854.

Types of pycnometers

As mentioned previously, there are pycnometers of different materials and each of them is used to analyze and measure specific substances. Some of the most used materials are:

- glass

- Metal

- Stainless steel

Gas pycnometer

It should be noted that there is a type of pycnometer called a gas or helium pycnometer, which was created by Abu Raihan Muhammad al-Biruni.

This type of instrument uses gravimetry as the main tool for measuring solid or liquid substances under a specific temperature.

It is used especially with porous materials and allows measuring their real density. This tool is one of the most used in chemical laboratories.

Also, many schools use this instrument because of its exact precision when measuring the density of both solid and liquid chemicals.

Pycnometer care

It is important to perform certain processes that will keep the pycnometer clean and accurate. For example, it must be calibrated although some come with automatic calibration.

If this is not the case, the entire instrument should be cleaned and dried with distilled water and acetone. This will allow the result to be the most correct and accurate.

References

1. Relative Density. Retrieved on September 13, 2017, from Wikipedia: en.wikipedia.org.
2. Gas Pycnometer. Retrieved on September 13, 2017, from Wikipedia: en.wikipedia.org.
3. Pycnometer. Retrieved on September 13, 2017, from Encyclopedia Britannica: britannica.com
4. Technical terms. Retrieved on September 13, 2017, from Analytical Flow Technologies: densitrak.com
5. Pycnometer. Retrieved on September 13, 2017, from Petropedia: petropedia.com
6. Rheology. Retrieved on September 13, 2017, from Wikipedia: en.wikipedia.org.
7. Determining Density Using the Pycnometer. Retrieved on September 13, 2017, from researchgate.net.