# How do I calculate concentration of hydrogen peroxide?



## rebel (23 Jul 2018)

Hi everyone,

Can someone point towards a resource that will help me understand the concentration calculation for hydrogen peroxide solution at 140g/L?

So far I got 34g/mol. So 140/34 = 4.1 mol/L. Does that mean 4%??

TIA!


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## zozo (23 Jul 2018)

What are you trying to do?... Mix it on your own from an higher concentration?.. Than you might need to keep in mind that a closed bottle has a 5 year shelf life but once a bottle is opened it might completely degrade in a month time because it's rather instable and i believe it's called auto Redox reaction, if stored at ambient temps and its warm it degrades even faster.

For example the highest concentration i can buy without permit is 50% in 1 litre bottle.. But i have no idea what to use it on to use it all up before its shelf life is over once the bottle is opened.


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## rebel (23 Jul 2018)

@zozo ,

Just wanted to compare two solutions for sale. One at 3% vs the other at 140g/L. 

Great tip regarding the auto redox. Will read up on it.


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## zozo (23 Jul 2018)

I guess that's your pitfall and makes a calculation only valid as long as the concentration in the botle is stable. But it isn't it slowly degrades than you need to add more of it after the bottle was openend and stored for a week. Only the % of degration on shellf life is probably not easy measurable.


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## zozo (23 Jul 2018)

But found this it might help you..
https://www.scientistsolutions.com/...s/how-calculate-molarity-30-hydrogen-peroxide


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## doylecolmdoyle (23 Jul 2018)

Interesting about it degrading, I use the 50% stuff straight into my tanks, about 10ml or so targeted to trouble areas via a syringe and long needle, I do notice that the h2o2 seems to be less effective once the bottle has been open for awhile.


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## zozo (23 Jul 2018)

doylecolmdoyle said:


> Interesting about it degrading, I use the 50% stuff straight into my tanks, about 10ml or so targeted to trouble areas via a syringe and long needle, I do notice that the h2o2 seems to be less effective once the bottle has been open for awhile.



I just know it does.. The rate in how fast will depend on how and with what it is compromised.. And it likely also depends on teh percentage, that 50% obviously stays longer active than 3%. But the reaction starts as soon as it comes in contact with air. With the 3% i once noticed it beeing less effective after a month after several times using it and opening the bottle. Also had a bottle about completely inactive after opening and forgetting about it for a while, i guess a few months dunno.. I always order 6 packs, than it can happen to forget about a already opened bottle put back at the wrong spot. 

Than i also must admint i'm quite sloppy.. Put a syrigne with the needle in the bottle than in the tank and back into the bottle.. Doing that x times before the bottle is empty it is contaminated each time again a bit. But usualy the bottle will be empty before its done reacting..


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## doylecolmdoyle (23 Jul 2018)

Yah i too am a bit sloppy and never clean the syringe of tank water when going back to the bottle. I never found the 3% stuff that effective, the 50% stuff seems to knock BBA out after 2 or so doses.


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## sparkyweasel (23 Jul 2018)

You can store it in an accordion bottle. It can be squashed down to exclude air.
eg:
https://www.amazon.co.uk/AP-Collaps...sr=1-1&keywords=Collapsible+++Chemical+Bottle


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## rebel (24 Jul 2018)

zozo said:


> But found this it might help you..
> https://www.scientistsolutions.com/...s/how-calculate-molarity-30-hydrogen-peroxide


Thanks!!! I am reading it now.


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## rebel (24 Jul 2018)

doylecolmdoyle said:


> Interesting about it degrading, I use the 50% stuff straight into my tanks, about 10ml or so targeted to trouble areas via a syringe and long needle, I do notice that the h2o2 seems to be less effective once the bottle has been open for awhile.


Doyle, where did you get that 50% stuff? I can't find it locally.


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## ian_m (24 Jul 2018)

doylecolmdoyle said:


> Interesting about it degrading, I use the 50% stuff straight into my tanks, about 10ml or so targeted to trouble areas via a syringe and long needle, I do notice that the h2o2 seems to be less effective once the bottle has been open for awhile.


Doubt you have 50% concentration. Hydrogen peroxide over 40% concentration is classified as explosive pre-curser and very strictly controlled in most countries. In fact 12% max is what the general public can get now. To get 35% (next grade up) you need to be licensed and is reportable if stored in any significant quantity in most of the world. This happened after the attempted use of 35% H2O2 and flour as bomb making compounds in 2005.


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## tiger15 (24 Jul 2018)

140g/l = 14% by weight

Here is the calculation:

140g/l = 140000 mg/l or 140000 ppm (since 1 liter pure H2O2 weighs 1000 mg)
1ppm = 1/1000000
1% = 1/100
Thus 1% = 10000ppm
So 140000ppm = 14%

Is the 140g/l more expensive than the 3% peroxide?  If so, my calculation is in the right direction.


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## sparkyweasel (24 Jul 2018)

I think a litre of peroxide weighs 1450 grammes. Pretty sure it's not 1000 miiligrammes.


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## tiger15 (24 Jul 2018)

sparkyweasel said:


> I think a litre of peroxide weighs 1450 grammes. Pretty sure it's not 1000 miiligrammes.


You are right.  I misspelled.  It wont change the calculation.  I meant 1 liter of pure H2O weighs 1000 grams, trying to explain why 1 mg/l in water is equivalent to 1 ppm by weight.


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## zozo (24 Jul 2018)

sparkyweasel said:


> I think a litre of peroxide weighs 1450 grammes. Pretty sure it's not 1000 miiligrammes.



From the link from scientistsolutions.com above 


> 3.2 Calculating the volume of 100 gram of H2O2 solution
> If one carefully read the bottle of H2O2 or Data sheet, *one may find the density of H2O2 solution. It is 1.11 g/ml*.
> Now calculate the volume of 100 gram of H2O2 solution using formula
> Density = Weight / Volume (See 2.3)
> Volume = Weight / Density



So Density H2O2 = 1.1g/ml x 1000 = 1100g/l



rebel said:


> concentration calculation for hydrogen peroxide solution at 140g/L?





> 3.3 Calculating the percentage concentration (weight/volume) of H2O2 solution
> Percent Concentration (Weight / volume)= 100 X Amount of solute (in grams) / Amount of solution (in ml)



 140g/l - 100x140/1000=14%


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## sparkyweasel (24 Jul 2018)

Marcel, 1.1g/ml is the density of the 30% solution, not pure peroxide. Doesn't affect the 14% calculation though.

But everybody's bottom line looks ok, 140g/l = 14% w/w.


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## rebel (25 Jul 2018)

Thanks all for the calculations!! Learn something new everyday!

The silly thing is that I can get a 5L 14% solution for about $60 or 200ml 6% for $4. 

Given the volatility of this compound I think I might have to stick with the 200ml versions. The issue is that some of the bottles are already denatured or reduced in intensity when I get them from the chemist, due to being in long storage I assume. It is not a commonly bought product I dont' think.


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## zozo (25 Jul 2018)

sparkyweasel said:


> Marcel, 1.1g/ml is the density of the 30% solution, not pure peroxide.


You are right.. Pure product is as you said 1,45 g/cm³ ..


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## doylecolmdoyle (25 Jul 2018)

rebel said:


> Doyle, where did you get that 50% stuff? I can't find it locally.



I get it from Aquotix here in WA, here are some photos



 



 



 



ian_m said:


> Doubt you have 50% concentration. Hydrogen peroxide over 40% concentration is classified as explosive pre-curser and very strictly controlled in most countries. In fact 12% max is what the general public can get now. To get 35% (next grade up) you need to be licensed and is reportable if stored in any significant quantity in most of the world. This happened after the attempted use of 35% H2O2 and flour as bomb making compounds in 2005.



Not sure, all i know is its says 50% Hydrogen peroxide on the bottle!


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## ian_m (25 Jul 2018)

You must be from country that has different rules (Australia ?, I think hasn't adopted the 12% rule).

In the UK, the same OxyOplus from Growth Technology is only 17.5%.





Which is very interesting as a member of the UK public wishing to get access to hydrogen peroxide above 12% must have a valid EPP (Explosives Precursors and Poisons) license. It is an offence to attempt to acquire or possess above 12% without a license. I don't think getting an EPP license is hard, proof of who you are and £39.50. The regulations below....


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## zozo (25 Jul 2018)

Initialy i didn't read correctly, we have webshops selling 50% but not without license..

EU regulation It's this one.. 
https://eur-lex.europa.eu/eli/reg/2013/98/oj



ian_m said:


> In the UK, the same OxyOplus from Growth Technology is only 17.5%.



Also in my country their are reports of shops not obliging this EU law. Mainly the shops with dental care products import from outside EU and sell it on.


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## ian_m (25 Jul 2018)

They did try to add potassium and sodium nitrate to the list, but they was removed as they are used in meat preservation, hydroponics and specialist fertiliser all areas where controlled legislation would make existing usage difficult and more importantly very hard to enforce/verify. Also there was no proof of misuse of nitrates.


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## rebel (25 Jul 2018)

Thanks @doylecolmdoyle , very interesting. I need to hunt around for that brand.

For teeth, carbamide peroxide is better than hydrogen peroxide AFAIK. I am no dentist tho.


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