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How do I calculate concentration of hydrogen peroxide?

rebel

rebel

Member
Joined
4 Aug 2015
Messages
2,265
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!
 
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.
 
@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.
 
🙂 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.
 
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.
 
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.
Click to expand...

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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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.
 
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.
Click to expand...
Doyle, where did you get that 50% stuff? I can't find it locally.
 
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.
Click to expand...
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.
 
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.
 
I think a litre of peroxide weighs 1450 grammes. Pretty sure it's not 1000 miiligrammes. 🙂
 
sparkyweasel said:
I think a litre of peroxide weighs 1450 grammes. Pretty sure it's not 1000 miiligrammes. 🙂
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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.
 
sparkyweasel said:
I think a litre of peroxide weighs 1450 grammes. Pretty sure it's not 1000 miiligrammes. 🙂
Click to expand...

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
Click to expand...

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

rebel said:
concentration calculation for hydrogen peroxide solution at 140g/L?
Click to expand...

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)
Click to expand...

140g/l - 100x140/1000=14% 🙂
 
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. 🙂
 
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.
 
rebel said:
Doyle, where did you get that 50% stuff? I can't find it locally.
Click to expand...

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

IMG_7858.jpg

IMG_7859.jpg

IMG_7861.jpg

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.
Click to expand...

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