LD5050 - 5-5-2017 at 19:25
I recently bought some 40 volume hydrogen peroxide from the hair salon supply store. I concentrated it by slowly evaporating off the water on my hot
plate. I found that it's concentration is around 70 percent. The ingredients labeled on the back were hydrogen peroxide and phosphoric acid. I want to
know how I should properly and safely store this now higher concentrated H2O2.
JJay - 5-5-2017 at 21:32
You don't want to store that stuff for very long. I'd probably put it in a very clean glass-stoppered bottle with the stopper placed loosely in the
neck.
LD5050 - 6-5-2017 at 11:09
Right now I have it stored in a small very clean amber bottle with a screw on cap with threads wrapped in teflon tape. I also keep it in my lab
fridge. Its pretty simple to make it just takes a long time so if I can safely keep it for a while I would like to. How long would I be able to store
it like this before it develops into something dangerous?
gdflp - 6-5-2017 at 11:24
What tests have you done to indicate that you have 70% H<sub>2</sub>O<sub>2</sub>? I'm rather skeptical that you were able to
concentrate it that easily.
phlogiston - 6-5-2017 at 14:00
Commercial 35% hydrogen peroxide comes in a black plastic bottles that have a special vent in the lid.
Adding a small amount of acid, minimising contaminants as much as possible (especially metals) and keeping it cold help to prolong its life, but it
can't be stored indefinitely.
macckone - 6-5-2017 at 20:01
Freeze it. The colder the better.
It is relatively stable when frozen.
LD5050 - 7-5-2017 at 16:12
I'm glad you asked. I'm not 100% sure of concentration but this is how I got a rough idea of it.
To determine the approx. concentration I filled a 100ml graduated cylinder full of water and placed it upside down in a beaker of water. I put a small
tube into the Grad. cylinder and attached the other end of the tube to a rubber stopper and fitted into a test tube loaded with .5ml of H2O2 and a few
mg of mangenese dioxide. When I mixed the two inside of the test tube it gave off O2 and the water level in the grad cylinder went to about 10 ml
above the 100ml mark.
So .5ml H2O2 gave off around 110ml of O2. If 40 volume (12%) H2O2 gives off 40 ml of O2 per 1ml of H2O2 and my 1ml H2O2 gave off 220ml O2 (.5ml=110ml
multiply by 2 =220) That means I have around 66% Hydrogen Peroxide (220/40=5.5 multiply by 12=66%)
I performed this process a few times and got the same results every time.
[Edited on 5-8-2017 by LD5050]
MrHomeScientist - 15-5-2017 at 06:09
Another way to find the concentration of hydrogen peroxide is to measure the density. Then you can use this handy calculator to determine concentration. I've done your method and the calculator, and they come out reasonably the same.
The 'captured gas' method is difficult to do accurately because of gas pressure in the system and the size of the bubbles coming out of the tube
leading to the measurement cylinder. If the tube is too large, the gas has to build up a bit before it releases a bubble. I have access to a very
accurate scale and volumetric flasks, so for me that method is better.