a humane way to euthanize feeders+ sad news for me+some questions about snake racks.

[Rhasputin]

There's that word again. Suffocating.
Death by Co2 is by definition asphyxia, but that doesn't mean they -can't- breath, it means they are not able to absorb enough oxygen. A lot of people seem to think it means the same thing as being smothered, or un-able to breath.
Here's a quote from wikipedia about the effects of CO2 on a human, "Without sufficient oxygen to sustain life, people will act normally at first but will then abruptly feel dizzy and black out in a matter of seconds as the remaining oxygen in the blood stream is consumed" this is what happens to the mice. There are also multiple instances where thousands of people died in their sleep, and many more died while they weer awake, due to an eruption of CO2 from underwater. None of the people woke up, struggled, or even felt bad. They would be talking, acting normal and just fall over and die. You can look up information about these instances online, in news papers, etc. This is direct human evidence and experience of the effects of CO2 on the body, and what death by CO2 feels like.
Now, go look up information about people dying or nearly so, from huffing canned air.
There are many ways to die from inhailing canned air, you don't know how your mice are dying for sure.

The mouse's body will be filled with whatever chemicals were in the gas, and being as it's dead, the chemicals will not be metabolized and turned harmles. By feeding these mice to your snake, your snake is ingesting potentially harmful chemicals. How you know how much of the chemical is in the rat/mouse, is beyond me. You haven't tested it, so you cannot know.

You're making some things up as you go, and using a method that you claim is better than one of the most widely used and accepted ways of euthanasia.
If you want to prove that it is better, then you need to use facts, not guesses, and misinformation.