Hydrogen Peroxide Gas Decomposition

Question

1. When using 3% hydrogen peroxide (type sold in brown bottle at drugstore) for home cleaning in the bathroom, once applied to tile or other bathroom surface, approximately how long does it take the hydrogen peroxide to break down? 5 minutes?  30 minutes? 2 hours?  Just looking for general estimate.

2. When using the 3% hydrogen peroxide for this purpose, is hydrogen peroxide released as a gas?  If so, once in the gaseous state, approximately how long will it last in air before breaking down?  5min? 30minutes? 2 hours? 

3.  What does the 3% hydrogen peroxide gas break down into? Anything harmful?

I realize there are many variables, however if you can provide any general time estimates at room temperature, I would be very appreciative.  Again, this is for kitchen and bathroom household cleaning use. I am asking from a safety respective.

Answer 1

Hydrogen peroxide actually takes a fairly long time to decompose on its own. That's why it can be sold in stores since it can remain on shelves for a long time. As you said there are many variables, but according to some sources a sealed container should last about 3 years and an opened container can last between 1 and 6 months. You can also check the bottle for an expiration date.

The decomposition of hydrogen peroxide is as follows: 2 H₂O₂ (l) --> 2 H₂O (l) + O₂ (g)

Therefore, yes the decomposition produces oxygen gas which is not harmful. Basically, hydrogen peroxide breaks down into water and oxygen over time where the decomposition can be catalyzed/sped up by UV rays from sunlight as well as warm temperatures. As long as you keep the hydrogen peroxide in the opaque bottle it is sold in and keep it away from sunlight the decomposition should be slow enough to where you should not be overly concerned.

If, at any point, you are concerned that your hydrogen peroxide has decomposed you can try testing it through various ways. You can check it's appearance. If it is a pale light blue then it's fine. If it is more transparent/colorless then it may have decomposed into water. If it is bubbling then it is decomposing and releasing oxygen gas. If you have pH paper you can test the pH since hydrogen peroxide is slightly acidic.