# what is the equation i should use to dilute 50% hydrogen peroxide into lower concentrations? Answered

hello, i just got some 50% hydrogen peroxide, from my local pharmacy because they were out of 35%, plus for some reason 50% is free.
anyways, i want to know whats the equation for finding out how many ml's of water i need to use to dilute a solution toa certain amount, as i want to use the 50% peroxide to make 30% , 22% and 3% peroxide.
now ive looked on google and i couldnt find a thing , and if i did by chance come across it, i didnt understand it.
what i want to know is how much distilled water will it take to convert 100ml of 50% hydrogen peroxide to the above concentrations, or if possible, could someone please give me the equation for converting any concentraion to any, please!

also, whoever answers my question and solved my problem entirely will get a best answr i promise!!!

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## Comments

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Since you have a 50% mixture of hydrogen peroxide, that is the highest you can go (without adding more hydrogen peroxide)... so given your 100ml... you have 50ml of hydrogen peroxide and 50ml of water... so the equation you have is...

50ml (hydrogen peroxide)/(100ml + added water) = percentage of hydrogen peroxide

Water to add (ml) = (50/Required percentage) - 100

So 30% you add... 66.6ml = (50/0.3)-100
For 22% you add... 127.3ml = (50/0.25) -100
for 3% you add... 1566ml = (50/0.03) - 100

I've never heard of a pharmacy carrying 50% H2O2.

The concentration is a direct ratio. If it is indeed 50% then you need to figure out how much peroxide there is in a given amount of concentrate (divide by 2) and then figure out how to make a different %.

100mL of H2O2 has 50mL of the magic juice.

If you want 3%, you need to add water inversely (cross multiply)

The equation above is for 100ml so for 10ml divide by 10...

But if you want...

Water to add (ml) = (ml of hydrogen peroxide)/Required percentage) - (ml of total liquid)

so for 10ml...

For 30% you add... 6.6ml = (5/0.3) - 10
For 22% you add... 12.7ml = (5/0.25) - 10
for 3% you add... 156.6ml = (5/0.03) - 10