Featured Research

from universities, journals, and other organizations

Scientists Discover Air Is Heavier Than We Thought

Date:
November 25, 2004
Source:
Institute Of Physics
Summary:
Scientists have discovered that the air in the atmosphere around us is heavier (more dense) than they had previously thought. Knowing this will enable scientists to measure the mass of objects more accurately than ever before.

Scientists have discovered that the air in the atmosphere around us is heavier (more dense) than they had previously thought. Knowing this will enable scientists to measure the mass of objects more accurately than ever before.

Related Articles


Writing in the Institute of Physics journal Metrologia, a team from the Korea Research Institute of Standards and Science (KRISS) and the International Bureau of Weights and Measures (BIPM) in France, report a new determination of the content of argon in air, the first since 1969.

If asked to name the major chemical components of air, most of us would list oxygen (about 21%), carbon dioxide (about 0.04%) and water vapour (typically about 1%). The principal component of air is nitrogen and the only other major component is argon (about 0.9 %). Argon is chemically inert and its presence in the atmosphere poses no problem to human well-being. Old measurements dating from as early as 1903 gave the content (moles of argon/mole of dry air) as 0.934 %. The most recent value available until now was lower (0.917 %) and was thought to supersede the previous result. The work reported in Metrologia gives a new figure (0.9332 ± 0.0006)%, very close to the measurement results of 100 years ago. The uncertainty in the new measurement is given at the 95% confidence limit and is of unprecedented accuracy.

The analysis was performed at KRISS using high precision mass spectrometry. A set of air-like calibration gas mixtures was prepared by very careful weighing of pure gases into high pressure cylinders. Analysis of these synthetic air mixtures along with samples of natural air contained in other high pressure cylinders yielded the result reported in Metrologia.

Argon content is important to a small community of scientists working on precision mass measurements. To understand why, think of the old puzzle: which weighs more, a kilogram of feathers or a kilogram of lead? If it were possible to do the weighing on a very precise balance, we would see that the balance readings are identical for the feathers and the lead if the weighing is carried out in a vacuum. But the feathers would produce a considerably lower balance reading for measurements in air. This is because feathers are more buoyant in air than is lead (Achimedes' Principle).

Mass metrologists use an equation to correct for the effect of air buoyancy. The equation includes the air density which, in turn, includes a parameter for the content of argon in the atmosphere. The different historical values for argon content lead to a difference in air density of just under 0.01%, or about 15 micrograms in the apparent mass of one kilogram made of stainless steel (15 parts in 109). The higher the argon content, the denser the air.

Even though the density of air is roughly 800 times smaller than water density, the effects of air buoyancy are easily seen in precise weighing. Thus the air density calculated from the new value of argon content should agree with precise data obtained from the feathers and lead experiment. There is a stainless-steel cylinder on one side, which is hollow inside, representing the low-density feathers. On the other, a thick-walled tube is a solid piece of stainless steel, thereby representing the high-density lead. The cylinder and tube have the same surface area, which simplifies analysis of the experimental data. The results of measurements with several different sets of hollow and solid objects are reported in a companion article in Metrologia, written by scientists at the BIPM and the Physikalisch-Technische Bundesanstalt, in Germany.

Michael Esler, from the Chemistry Section at BIPM, and one of the authors, said: "The results confirm the new argon content and can explain discrepancies that had already been observed using the previously-accepted value dating from the mid-20th century. The new determination of argon content was motivated by numerous mass measurements which stubbornly failed to agree with the accepted formula for air density. The new results should lead to improved coherence among high precision mass measurements".


Story Source:

The above story is based on materials provided by Institute Of Physics. Note: Materials may be edited for content and length.


Cite This Page:

Institute Of Physics. "Scientists Discover Air Is Heavier Than We Thought." ScienceDaily. ScienceDaily, 25 November 2004. <www.sciencedaily.com/releases/2004/11/041123112014.htm>.
Institute Of Physics. (2004, November 25). Scientists Discover Air Is Heavier Than We Thought. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2004/11/041123112014.htm
Institute Of Physics. "Scientists Discover Air Is Heavier Than We Thought." ScienceDaily. www.sciencedaily.com/releases/2004/11/041123112014.htm (accessed October 25, 2014).

Share This



More Matter & Energy News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

IKEA Desk Converts From Standing to Sitting With One Button

IKEA Desk Converts From Standing to Sitting With One Button

Buzz60 (Oct. 24, 2014) — IKEA is out with a new convertible desk that can convert from a sitting desk to a standing one with just the push of a button. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Ebola Protective Suits Being Made in China

Ebola Protective Suits Being Made in China

AFP (Oct. 24, 2014) — A factory in China is busy making Ebola protective suits for healthcare workers and others fighting the spread of the virus. Duration: 00:38 Video provided by AFP
Powered by NewsLook.com
Real-Life Transformer Robot Walks, Then Folds Into a Car

Real-Life Transformer Robot Walks, Then Folds Into a Car

Buzz60 (Oct. 24, 2014) — Brave Robotics and Asratec teamed with original Transformers toy company Tomy to create a functional 5-foot-tall humanoid robot that can march and fold itself into a 3-foot-long sports car. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Police Testing New Gunfire Tracking Technology

Police Testing New Gunfire Tracking Technology

AP (Oct. 24, 2014) — A California-based startup has designed new law enforcement technology that aims to automatically alert dispatch when an officer's gun is unholstered and fired. Two law enforcement agencies are currently testing the technology. (Oct. 24) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins