20-Volume questions ????? OCR Chemistry

7

Hi,

I have a problem with this question.

Hydrogen peroxide readily decomposes to give water and oxygen.
Hydrogen peroide is sold by volume strength. For example 20-Volume H202 (hydrogen peroxide) yields 20 volumes of oxygen gas for each volume H2O2 solution.

i.) construct an equation for the decomposition of Hydrogen peroxide
I can do this part
................................................................................

ii.) Determine the concentration in mol dm-3, of 20 volume Hydrogen peroxide. Show all your working clearly.

Any one help casue i have no idea where to start. :frown:

Reply 1

charikaar

Redeyejedi

Hi,

I have a problem with this question.

Hydrogen peroxide readily decomposes to give water and oxygen.
Hydrogen peroide is sold by volume strength. For example 20-Volume H202 (hydrogen peroxide) yields 20 volumes of oxygen gas for each volume H2O2 solution.

i.) construct an equation for the decomposition of Hydrogen peroxide
I can do this part
................................................................................

ii.) Determine the concentration in mol dm-3, of 20 volume Hydrogen peroxide. Show all your working clearly.

Any one help casue i have no idea where to start. :frown:

you didn't state unit for volume i.e cubic centimeter or litres?

Reply 2

Redeyejedi

OP

7

dm^3

oh and if you want to see the question its here..

http://www.emailed.org.uk/exams/2816_1_Jan_04QP.pdf

questions 2c and 2d

thanks

Reply 3

Brigand

i assume that by 20 volumes of O₂ for each volume of H₂O₂ the question means that volume ratio of O₂ :h:

₂O₂ is 20:1
therefore say that means 1dm³ H₂O₂ and 20 dm³ O₂

1mole of O₂ occupies 24dm³
therefore
20/24=0.833 moles O₂

as the mole ratio O₂ :h:

₂O₂ is 1:2 (1mole of O₂ is produced from every 2moles of H₂0₂
there are 0.833*2=1.67moles H₂O₂

Concentration = moles/volume
=1.67/1
=1.67moldm^-3

i'm not at all sure whether thats right but it's the best i can come up with

Reply 4

Redeyejedi

OP

7

Thanks for your help

20-Volume questions ????? OCR Chemistry

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