[billnotgatez]

Any comments about this list I made
I attached a text file with a better layout

GAS                    MW              PROPERTY
Hydrogen, H2           02.02 g·mol−1   flammable
Helium                 04.00 g·mol−1   inert
Methane CH3            16.04 g·mol−1   flammable
Ammonia                17.03 g·mol−1   caustic
Water (steam) H2O(v)   18.02 g·mol−1   hot
Hydrogen fluoride HF   20.01 g·mol−1   caustic
Neon Ne                20.18 g·mol−1   inert
Methyllithium LiCH3    21.98 g.mol−1   caustic
Acetylene HCCH         26.04 g.mol−1   unstable
Hydrogen cyanide HCN   27.03 g·mol−1   toxic
Diborane B2H6          27.67 g.mol−1   unstable
Carbon monoxide CO     28.01 g·mol−1   toxic
Nitrogen N2            28.01 g·mol−1   
Ethylene H2CCH2        28.05 g·mol−1   flammable
Air                    28.97 g·mol−1   

[billnotgatez]

If I had air at the beginning in 22.4 L flask at 1 Atm and 0C and was 1 mole
would the same flask have only .73 mole when heated to 100 C and allowing the gas to escape.

would the molecular weight then be 28.97 * .73 = 21.21 g.mol-1

[Borek]

Methane is CH₄.

Are you sure methyllithium classifies as gas?

While I think understand the idea behind your statement

would the molecular weight then be 28.97 * .73 = 21.21 g.mol-1

I have a hard time agreeing with it. Molar mass is not something temperature dependent. You are referring to apparent molar mass relative to some other gas hold at STP. Convoluted. Could work if used for calculations in some particular cases, but dangerous in general - it may give a false feeling you know what you are doing using it and yield completely wrong answers if used blindly.

[billnotgatez]

http://www.answerbag.com/q_view/5923
said methyllithium was but not the same spelling

i think i have to footnote the list to say apparent for steam and hot air

i assume you do agree with the .73 mole

[billnotgatez]

maybe it would be better to use density rather than MW