How to Make Oxygen Gas
Oxygen. O2. It's an element that we are all familiar with, and it's an element that is an integral part of many molecular compounds. We breath it in, we breath it out, and we could even be breathing in the same oxygen molecules breathed by important figures in history. Just mind-blowing! Oxygen is diatomic, which means, that as a gas, it must be bonded to another oxygen in order to exist in that state. Oxygen fuels fire, rockets, biological and chemical processes, and most importantly, our bodies. So, how difficult is it to make this essential gas? Let's get started, and you will see for yourself!
First, let's gather the materials that we will need:
- Bleach (Sodium hypochlorite or NaClO; 6%)
- Hydrogen Peroxide (or H2O2; 3%)
- Longneck Glass Bottle
The first step is to measure out about 50ml of bleach (see photos for reference if you don't have anything to measure with) and pour it carefully into the bottle, avoiding the sides of the neck as much as possible to avoid a premature reaction. Set that aside.
Next, fill a balloon with hydrogen peroxide by attaching it to the mouth of the bottle, and allowing gravity to fill it (don't "inflate" it with hydrogen peroxide like you're filling a water balloon, only fill it to capacity unpressurized). Make sure that the neck of the balloon is clear of hydrogen peroxide so as to avoid a premature reaction.
Next, slip the balloon over the mouth of the glass bottle, and pinch the sides to hold it in place. Tilt the bottle and slowly lift the balloon filled with hydrogen peroxide so it begins to pour into the bottle. The reaction between the two is immediate and volatile, but you can control it by slowing the flow of hydrogen peroxide into the bottle. Once it's stopped reacting (foaming), tap the balloon to shake out any residual hydrogen peroxide. Pull the balloon off, and tie it (see video below for complete demonstration).
Pouring the Hydrogen Peroxide
You now have a balloon filled with oxygen! You don't have to worry about it floating away since oxygen is heavier than air. I would not recommend inhaling it, as it may have residual bleach fumes, which are not fun to breath. So, before we continue, let's take a look at what happened.
The equation for the reaction is as follows:
NaClO (Bleach) + H2O2 (Hydrogen Peroxide) --> NaCl (Salt) + H2O (Water) + O2 (Oxygen Gas)
Basically, we have turned something as toxic as bleach into something as inane as salt water! You will notice that the color of the bleach changes from yellow before the reaction to clear afterwards. That's because we have completely rearranged the molecular structure so that it displays completely different properties. In fact, if you smell the bottle, it will smell chlorinated (like it's been disinfected), but otherwise, it no longer smells like bleach!
As a secondary part of this experiment, you can evaporate the remaining liquid and be left with pure NaCl, otherwise known as table salt (I wouldn't recommend eating it, though). If you evaporate it in a shallow dish in the sun, you will be left with salt crystals, which are perfectly cubic (see photo)! This is due to the molecular arrangement of the Na (sodium) and Cl (Chlorine) atoms in the structure. In fact, you can take the salt off of your own table, stick it under a microscope, and you will see a bunch of perfect cubes.
Now, what do we do with that balloon filled with oxygen? Blow it up, of course! Oxygen is flammable, but it does not produce a colored flame. In this experiment, I taped the balloon to a mop stick and lowered in onto a tealight. See the video below for the loud pop that it makes. It's not as impressive as my Hydrogen Video, but it's still pretty cool.
Feel free to comment, and ask any questions that you may have!