# Dilution of Hydrogen Peroxide

Namkceis
< Mentor Note -- thread moved to HH from the technical forums, so no HH Template is shown >

The experiment I'm trying to do can be found in the attachment below.

Prepare 20 mL solutions of hydrogen peroxide in the following concentrations: 0%,0.5%, 1.0%, 1.5%,
2.0%, 2.5%, 3.0% hydrogen peroxide.

I'm starting with hydrogen peroxide at 3% concentration. How do I to get these concentrations? What measurement tools do you need to do this? I'm not a chemist so I have no idea. Is it dilution?

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Homework Helper
Gold Member
Is it dilution?
Yes.
How do I to get these concentrations? What measurement tools
These are mass percentages. Properly you add a large enough mass of water to a weighed amount of 3 % solution so that the total mass of hydrogen peroxide divided by the total mass of solution is the percentage you're interested in having.

For practical purposes, you can consider the density of water and of starting and ending solutions to be one, and use a volumetric flask.

Staff Emeritus
Homework Helper
The 0% concentration seems odd. It's just 20 ml of water.

Homework Helper
Gold Member
The 0% concentration seems odd
Odd, but not uncommon. Specifically states the obvious point that effects of a particular agent/reagent/compound are compared to situations where no effects are possible. A global specification would be that the solution be 0% {all 20-30M compounds listed in the CAS Registry}.

Namkceis
Yes.

These are mass percentages. Properly you add a large enough mass of water to a weighed amount of 3 % solution so that the total mass of hydrogen peroxide divided by the total mass of solution is the percentage you're interested in having.

For practical purposes, you can consider the density of water and of starting and ending solutions to be one, and use a volumetric flask.

Thank you for your response and willingness to assist me.

total mass of hydrogen peroxide / total mass of solution = % concentration after dilution

example:
x / 1 = 0.5%
x = 0.5%

total solution = 20 mL

20 mL - 0.5 = 19.5 mL

or is it...

20 mL - 0.005 = 19.995 mL

-----------------------------------
How does density fit into all this?
I know Density = Mass / Volume.
The density of water is 999.97 kg/m3 = Mass / Volume. Is the mass 20 mL?

Last edited:
Homework Helper
Gold Member
My bachelors degree required many philosophy credits so I know a bit about philosophy.
x = 0.5%
total solution = 20 mL
20 mL - 0.5 = 19.5 mL
or is it...
20 mL - 0.005 = 19.995 mL
Good one.

Namkceis
Good one.