Creating Different Concentrations of Hydrogen Peroxide

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Discussion Overview

The discussion revolves around preparing different concentrations of hydrogen peroxide solutions, specifically focusing on how to dilute a 3% hydrogen peroxide solution to achieve concentrations of 0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0%. Participants explore the methods of dilution, measurement tools, and the implications of density in the calculations.

Discussion Character

  • Technical explanation
  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant asks whether dilution is the correct method to achieve the desired concentrations.
  • Another participant confirms that dilution is indeed the method and explains that mass percentages are involved, suggesting the addition of water to a weighed amount of the 3% solution.
  • Concerns are raised about the 0% concentration, with one participant noting it is simply 20 mL of water.
  • A later reply clarifies that having a 0% concentration is not uncommon, as it serves to compare the effects of the hydrogen peroxide with a control solution.
  • Participants discuss the formula for calculating concentration after dilution, emphasizing the relationship between total mass and percentage concentration.
  • Questions arise regarding how density fits into the calculations, with one participant recalling the formula for density and inquiring about the mass of 20 mL of water.

Areas of Agreement / Disagreement

There is no consensus on the interpretation of the 0% concentration, with some participants finding it odd while others defend its relevance. The discussion remains unresolved regarding the specifics of the calculations and the role of density.

Contextual Notes

Participants express uncertainty about the correct calculations for achieving the desired concentrations, particularly in relation to the mass and volume of solutions. There are also unresolved questions about the implications of density in these calculations.

Who May Find This Useful

This discussion may be useful for individuals interested in chemistry experiments, particularly those involving solution preparation and dilution techniques.

Namkceis
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< 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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Namkceis said:
Is it dilution?
Yes.
Namkceis said:
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.
 
The 0% concentration seems odd. It's just 20 ml of water.
 
SteamKing said:
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}.
 
Bystander said:
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:
Namkceis said:
My bachelors degree required many philosophy credits so I know a bit about philosophy.
Namkceis said:
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.
 
Bystander said:
Good one.

Thank you for your helpful guidance.
 
Thanks
 

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