How to Make Hydrogen Gas
This is an incredibly easy experiment that you can do at home (although, I recommend that you do the Hydrogen explosion outside). This fun with chemistry will allow you to make the most abundant element in the universe, Hydrogen. Not only is it the most abundant element, but it also one of the coolest to light on fire (which we all love!).
The materials that you will need to acquire are (no specific measuring necessary):
- White Vinegar
- Magnesium Fire Starter Block (lots of brands out there, about $8-$10)
- Longneck Glass Bottle (washed)
- Rubber Band
First thing that you need to do is cut the magnesium block in half (if necessary) so that it'll fit into the bottle opening. Magnesium is a 2.5 on the Mohs harness scale, so it is pretty easy to cut with a hacksaw. In comparison, aluminum (aluminium for my fellow Brits!) is a 2.75 on the Mohs hardness scale. So, cutting magnesium is pretty comparable to cutting a piece of aluminum.
The next step is to fill the bottle with vinegar to a level that will at least fully submerge the magnesium block (don't add the block, yet!). I filled the bottle just past the top of the front label.
Next, attach a rubber band near the mouth of the bottle so it can be rolled onto the balloon's lip once it is placed over the mouth.
NOW, you can drop the magnesium block into the vinegar. It will begin reacting immediately, but don't panic! The release of hydrogen may seem volatile, but the volume of hydrogen being released is minimal (see first video at the bottom of the page). Also, you don't have to worry about wasting your magnesium by taking your time to attach the balloon, since the amount of magnesium lost to fill an entire balloon with hydrogen is very small.
Now, you can slip the balloon over the mouth of the bottle. Hold onto the sides of the balloon while you roll the rubber band over the lip of the balloon. This part can be difficult depending on the thickness of the rubber band you choose and how tightly you initially attached it to the bottle.
Now, just sit back, and wait. And wait. And wait. This experiment took an hour to fill a 7" balloon to capacity. Once your balloon is inflated to your desired size, remove it and tie it. REMEMBER!: Hydrogen is less dense than helium, so if you let go of the balloon accidentally, that baby will fly!
Next, pour out the vinegar from the bottle so that the magnesium will stop reacting. When you take the magnesium out, it will have a black oxide coating on it, which washes off really easily. Another cool feature that you will notice is that the magnesium block will now have a texture similar to sandpaper or pumice. This is due to the atoms of magnesium being pulled away from the block to release the hydrogen from the vinegar. Pretty cool, huh?
You are now ready to light your hydrogen balloon! I taped my balloon to a mop stick and lowered it onto a tealight. Conversely, some people tether the balloon to a weight and ignite it with a match-on-a-stick. Personally, I like to get as far away as possible. See the video at the bottom of the page for the awesome explosion (I apologize ahead of time for the burst of frightened laughter following the explosion. Skiddish camera operator).
Feel free to comment and ask me any questions that you may have. Enjoy!