[dana]

Hello!
How can i make 100ml solution of H₂O₂  10^-5 M from H₂O₂ 30%,knowing that Molecular Weight for H₂O₂ is 34.01 and density is 1.4g/cm ³
Thx very much
    

[Borek]

How many moles of H₂O₂ you need? What mass do they have? What mass of 30% solution contains required amount of H₂O₂? What volume is it?

Answer each question in the order they are asked and you'll be home.

[dana]

I need to make 100ml of H₂O₂ 10^-5 M , from H₂O₂ 30%(M= 34g/mole, density= 1.10g/cm ³)  . Unfortunately this is all i have. I myself choosed this volume (100ml) but it can be more then 100ml or less, has no importance, what is important is the molarity (10^-5 M)
Best regards and thank you for answearing.

[dana]

So i fallowed your instructions and my result is 1.03microliters/1000ml but it must be an error cos this volume is too small

[DevaDevil]

10^-5 mol is a very small concentration as well.

btw, first you state density = 1.4 g/cm³ and then 1.1; what is it?


now 100 ml of 10^-5 peroxide: 0.1 l * 10^-5 mol/l = 10^-6 mol
10^-6 mol * 34 g/mol = 3.4 * 10^-5 g peroxide needed
3.4 * 10^-5 g / 1.4 g/cm³ = 2.42 * 10^-5 cm³ peroxide needed
30%: 2.42 * 10^-5 cm³ / 0.30 = 8.1 * 10^-5 cm³ =  8.1 * 10^-5 ml = 8.1 * 10^-2 microliter


So yes, your answer is right if you use density 1.1 g/cm³

in order to make a solution like that it is wise to make a less-dilute concentration first (say 10^-3 M) and then dilute that

[Borek]

So yes, your answer is right if you use density 1.1 g/cm³

1.1122

[mir]

Hello!
How can i make 100ml solution of H₂O₂  10^-5 M from H₂O₂ 30%,knowing that Molecular Weight for H₂O₂ is 34.01 and density is 1.4g/cm ³
Thx very much
    

Also try this site...
http://www.chembuddy.com/?left=concentration&right=percentage-to-molarity