Nitrogen vs Air in Car Tyres

The tread on my car tyres had worn down, so I popped into my local tyre retailer to buy 4 new tyres.

"We can inflate your new tyres with air, or, for an extra $5 per tyre we can fill them with nitrogen gas", the sales person told me, " Nitrogen gas doesn't react with tyre and rim material so your tyres will last longer, it will help maintain the pressure in your tyres so you won't need to check your tyre pressure as often, and it reduces the running temperature of the tyres so your tyres are less likely to explode."

Is this just marketing hype or are there good reasons for choosing to inflate your car tyres with nitrogen instead of air?

Read the March 2020 edition of AUS-e-NEWS to find out more.

Subscribe to AUS-e-NEWS, AUS-e-TUTE's free quarterly newsletter for chemistry teachers and students, at https://www.ausetute.com.au/ausenews.html

Mendeleev's Biggest Failure

2019, the International Year of the Periodic Table, marks the 150^th anniversary of Dmitri Mendeleev's formal presentation of his Periodic Table to the Russian Chemical Society on 6^th March 1869.
His Periodic Table is arguably the most important breakthrough in the history of Chemistry because it not only organised the elements into groups based on their properties, it also continues to allow us to make predictions about the physical and chemical properties of elements.
Yet, despite its predictive capacity, Mendeleev failed to predict an entire group of elements!

Read all about it in the March 2019 issue of AUS-e-NEWS.

Subscribe to AUS-e-TUTE's free quarterly newsletter AUS-e-NEWS at 

https://www.ausetute.com.au/ausenews.html 

New Nitrogen Oxide Compound

Chemists already know about a number of compounds composed of nitrogen and oxygen:

• Nitric oxide is a colourless gas which is produced during the combustion of fossil fuels. It has a melting point of -163.6^oC, a boiling point of -150.8^oC, and rapidly oxidizes in air to form nitrogen dioxide. Its solubility in water is 7.4ml/100ml.
  
• Nitrogen dioxide is a reddish-brown toxic gas. Its melting point is -11.2^oC and its boiling point is 21.1^oC. It reacts with water to produce nitric acid.
• Nitrous oxide is a colourless gas commonly referred to as laughing gas. It is a greenhouse gas and also causes ozone depletion. Its melting point is -90.86^oC and its boiling point is -88.48^oC. Its solubility in water is 0.15g/100ml.
• Dinitrogen trioxide is a deep blue liquid at low temperatures. It has a melting point of -100.1^oC, a boiling point of 3^oC , and is very soluble in water.
• Dinitrogen tetroxide is a colourless liquid which is a powerful oxidizing agent and highly toxic. Its melting point is -11.2^oC, its boiling point is 21.1^oC, and it reacts with water to produce both nitrous aid and nitric acid.
• Dinitrogen pentoxide exists as colourless crystals. It is unstable and potentially dangerous oxidizer. It has a melting point of 30^oC and it sublimes at 47^oC. Dinitrogen pentoxide reacts with water to produce nitric acid.
  

Chemists at the Royal Institute of Technology in Sweden have discovered a new molecule in this nitrogen oxide group. The new molecule, composed only of nitrogen and oxygen, is called trinitramid. Trinitramid has the chemical formula N(NO₂)₃ and is shaped like a propeller.

Reference
Martin Rahm, Sergey V. Dvinskikh, István Furó, Tore Brinck. Experimental Detection of Trinitramide, N(NO₂)₃. Angewandte Chemie International Edition, 2011; (forthcoming)

Further Reading
Molecular Mass
Percentage Composition
Definitions of a Mole
Mass-Mole Calculations
Lewis Structures
Intermolecular Forces

Study Questions

1. Give the chemical formula for each of the following molecules:
   • nitric oxide
   • nitrogen dioxide
   • nitrous oxide
   • dinitrogen trioxide
   • dinitrogen pentoxide
2. Calculate the molecular mass (formula weight) of each of the molecules above.
3. Calculate the percentage composition of each of the molecules above.
4. Draw a Lewis Structure (electron dot diagram) for each of the molecules above.
5. Use the information in the article above, as well as your calculations, tabulate the melting points, boiling points and solubility of each molecule.
6. Graph melting points and boiling points against molecular mass.
   
7. Can you identify any trends in the melting points, boiling points, or solubilities of these molecules? Explain any trends you identify.
8. So far, scientists have only produced enough trinitramid to detect it. What do you predict its melting point, boiling point and solubility in water to be? Explain your answer.
   

Stripping Neon

The Linac Coherent Light Source (LCLS) delivers an intense pulse of X-rays designed to image atoms and molecules.
When the LCLS X-rays are tightly focused by mirrors, each pulse destroys any sample it hits.

LCLS pulses have been used to strip electrons away from atoms of neon one at a time.
Using a shorter pulse, fewer electrons are stripped away and less damage is done.
By varying the photon energies of the pulses, the electrons can be removed from the outside in, or, from the inside out creating so-called " hollow atoms".

The 2 electrons in the innermost electron shell closest to the nucleus are the hardest to strip away, but they also most readily absorb photons of X-ray light and so are the most vulnerable to being stripped away by intense X-rays. At low photon energies, the outer electrons are removed, leaving the inner electrons untouched. At higher photon energies the inner electrons are the first to be ejected, then the outer electrons cascade into the empty inner core, only to be kicked out by later parts of the same X-ray pulse.

Reference:
L. Young, E. P. Kanter, B. Krässig, Y. Li, A. M. March, S. T. Pratt, R. Santra, S. H. Southworth, N. Rohringer, L. F. DiMauro, G. Doumy, C. A. Roedig, N. Berrah, L. Fang, M. Hoener, P. H. Bucksbaum, J. P. Cryan, S. Ghimire, J. M. Glownia, D. A. Reis, J. D. Bozek, C. Bostedt, M. Messerschmidt. Femtosecond electronic response of atoms to ultra-intense X-rays. Nature, 2010; 466 (7302): 56 DOI: 10.1038/nature09177

Study Questions

1. What is the name given to the removal of electrons from a gaseous atom?
2. What is the charge resulting from the removal of an electron from a neon atom?
3. Write the electron configuration for the neon atom and for the species produced after an electron has been removed.
   
4. Write an equation to show the removal of an electron from a gaseous neon atom.
5. In a similar set of experiments, nitrogen was used instead of neon. Write the electron configuration of a nitrogen atom and of the species produced after an electron has been removed.
6. Do you think it would be easier to remove an electron from an atom of neon or from an atom of nitrogen? Explain your answer.
7. Why do you think the researchers chose to use neon and nitrogen gases for these experiments?