Chemical Vacuum "Pump"

It appears that lithium will react with nitrogen at room temperature to form solid lithium nitride. It looks like it will also oxidize. So if some quantity of finely powdered mostly pure lithium is placed in a sealed container, possibly up to 99% of the air will react and turn to a solid, creating a low vacuum. I was starting to try to figure out if other gasses could be captured, like CO2, etc, but realized that's pointless since almost 1% of air is argon, which won't react with anything.

So what would this be good for? Well vacuum pumps are expensive, and if you just need to create a vacuum on rare occasions, this might be just the thing. Ideally this could be sold in a tea-bag-like pouch sealed inside a foil wrapper. Tear the foil open, toss it in the container and close the lid. You might want to shake it around a bit (after eh lid is closed) to help the air distribute throughout the powder more quickly. I envision using this for the feather drop experiment in classrooms with a long clear tube. When you first throw the pouch and feather into the tube, turning the container over will result in the pouch falling faster than the feather. As the vacuum is improves, the feather will fall faster and faster.

To get a higher vacuum, the container could be purged with nitrogen to reduce the concentration of argon and any other gasses that won't react with lithium.

Still unresolved (since I'm too lazy to research this at the moment): Just how dangerous is pure lithium? I don't suppose the US Postal Service would want to deliver this. If it's packed to look like a tea-bag, how do we ensure that no one drops it in a cup of hot water? How do you safely dispose of the lithium Nitride when you're done? How much finely powdered lithium would be needed per quart of air at sea level, and how expensive would that be?