What are some interesting facts about chemistry?

 

• A rubber tire is technically one single, giant, polymerized molecule.

• Lightning strikes provide the energy to "crack" O2 oxygen molecules into radicals which can reform into O3 (ozone). Hence the characteristic smell after lightning storms.
  
  
• More on O3 and rubber: ozone attacks the double bonds in elastomers such as tires and rubber tubing, in a process known as ozonolysis, which disrupts the neatly polymerized structure.
  
  

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  Only a tiny amount of ozone is needed to initiate the cracking. Eventually they take on this familiar appearance:

• Hydrofluoric acid HF is so violently corrosive it will dissolve virtually every earthly substance, with the exception of polyethylene or fluorocarbon plastic, lead or platinum. It is still classified as a "weak acid" - a source of confusion for many.

• The weight you lose as a result of working out is lost as CO2 and H2O vapor. Obvious in a way, but still impressive when you consider the sheer mass of that gas.

• The letter J does not appear in the periodic table.

• The frivolous use of helium in party balloons is building up towards a global shortage of the element, despite it being the second most abundant element in the universe. Helium is important in a number of industrial processes, and the shortage has sent helium prices sky high (pun intended). It is estimated that by 2020 there will be no more commercially available helium, at least for private individuals.
  
  [Source: http://www.telegraph.co.uk/science/9500575/Party-balloons-at-risk-as-helium-prices-go-up.html]

• Apples and pears release ethylene gas as they mature, which in turn can promote ripening in several other types of fruit. In other words it is not the best idea to store all your fruit together.
  
  
• Adding highly halogenated side groups increases the lipophilic character of a drug. Entirely counterintuitive (at least to me).
  
  

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• Copper(II) acetoarsenite, also known as Paris Green, was historically used in the Napoleonic era as a color pigment by painters, and on wallpapers. Come spring, the humidity in the air would allow molds to process the paint's arsenic atoms into arsine vapor AsH3, which is a deadly poison. As a result, a number of people fell ill or outright died around spring at the hands of their green wallpapers.
  

• Automotive airbags contain the supremely toxic salt sodium azide NaN3. In the event of a collision, a signal from the vehicle's deceleration sensors trigger an electrical impulse which raises the temperature around the salt dramatically, causing it to decompose into harmless nitrogen gas N2 which rapidly expands into the airbag.