Inert Atmosphere??

[Hippieduster]

When using an Inert Atmosphere (N20)do you have to keep it a steady stream or use a ballon (N20)? This puzzled me after reading something on the net. From what I know I believe it should be a steady stream,but I am not sure.

[Barium]

It depends on what you are doing. A baloon can be used for a closed system in which there is no gas evolved in the reaction and a stream is used when there is gas evolved. In the latter case you can´t have a closed system. I haven´t seen N₂O (nitrous oxide, laughing gas) been used as a inert gas because it can act as a oxidizing agent, but N₂ (nitrogen) is the most commonly used inert gas because it reacts with very few things.

[amalgum]

Helium works just as well.  Also cheap and easy to get.

[Natrix]

Argon is cheaper than helium.

[Rhodium]

And nitrogen even cheaper...

A disadvantage of Helium compared to Argon (both completely inert though) is that it is so light as to easily escape the reaction setup.

[Barium]

Argon is heavy enough for you to actually be able to, if you are quick and have gentle hands, open the reaction setup to make some adjustments without disturbing the inert atmosphere too much. Argon is also soo much cheaper than helium. A 50L (@ 200 bar) nitrogen cylinder costs me about $30 to refill while a argon cylider of the same size costs me about $100. Nowdays I use both but I used to only go for argon in the past.