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Monday, October 15, 2018

VOLUME STRENGTH OF H2O2(aq)

 Hydrogen peroxide is a colourless liquid used as bleaching agent in some food and act as oxidising as well as reducing agent.The most common use of hydrogen peroxide is in cosmetic including personal care, hair dye, bleach shampoos conditioners and first aid  antiseptic.
Hydrogen peroxide also used as propellant for torpedoes on account of its exothermic decomposition.
The strength of Hydrogen peroxide expressed several ways like Volume strength, W/V % (% strength), Molarity, Normality etc.

COMMERCIAL LABELLING OF H2O2 AS ‘X’ VOLUME :  
Commercially H2O2 labelled as 'X' volume H2O2 (at P=1 ATM and T=273 K)
Where 'X' may be  10V, 20V, 30V, 40 V etc. 

Here  'X' Volume H2O2 means that 1ml of such solution of hydrogen peroxide on decomposition  produce 'X' ml of oxygen (at P=1 ATM and T=273 K).
For example 10 Volume H2O2 means that 1ml of such solution of hydrogen peroxide on decomposition  produce '10' ml of oxygen (at P=1 ATM and T=273 K).

W/V % or PERCENTAGE STRENGTH OF  H2O2SOLUTION: 
The amount of H2O2 in gram present in 100 ml of aqueous solution of H2O2. Called (w/v) or percentage strength.

Illustration:  taken 10 V (Vol) H2O2:

By Stoichiometric calculations:

Thus 1ml, 10 V labelled H2O2 (aq) solution contains 0.0303 gm H2O2.
Similarly 100 ml, 10 V labelled H2O2 (aq) solution contains 0.0303x100=3.03 gm of H2O2. This called W/V % or percentage strength of H2O2 solution.

MOLARITY AND NORMALITY OF H2O:
 And 1000 ml, 10 V labelled H2O2 (aq) solution contains 0.0303x1000=30.30 gm H2O2. It means 30.30 gm H2O2 dissolved in 1000 ml (1L) Solution.

  Hence Molarity of 10 V H2O2 Solution is = 0.89 M
  Normality of 10V H2O2 (aq) Solution: 
Hence Normality of 10 V H2O2 Solution is =1.79 N
 We also know that NORMALITY= MOLARITY X n-FACTOR
                              Normality= O.89x2 =1.79 N

ALTERNATIVE MATHAD TO DTERMINED MOLARITY AND NORMALITY:
Volume of O2 provided by 1unit Volume of H2O2 aq Solution
ILLUSTRATIVE EXAMPLES:
EXAMPLE: (1) A solution of H2O2 has Normality N/1.7 calculate w/V strength of this solution?.
EXAMPLE: (2) Convert 20 V H2O2 into % strength or w/v strength?
EXAMPLE: (3) Convert 6.8 % strength of H2O2 into Volume strength?
EXAMPLE: (4) 500 ml of a H2O2 solution on decomposition produce 2 mole of H2O. Calculate the Volume strength of of H2O2 of solution? (Given Volume of O2 measured at 1atm and 273 K)  (Ans - 44.8 V)
EXAMPLE: (5) What is the percentage strength of "15" volume of H2O2?
EXAMPLE: (6) What volume of H2O2 solution of "11.2 volume strength is required to liberate 2240 ml of O2 at NTP?
EXAMPLE: (7) 30 gm Ba(MnO4)2 sample containing inert impurity completely reacting  with 100 ml "28" volume strength of H2O2 in acidic medium then what will be the percentage purity of Ba(MnO4)2 in the sample ?. (Ba=137, Mn = 55, O =16)
EXAMPLE: (8) the strength of "20 Volume" H2O2 is equal? 
EXAMPLE: (9) What is weight of available oxygen from a solution of H2O2, if 20 ml of this solution need 25 ml, N/20 KMnO4 for complete oxidation? (Ans- 0.25)
EXAMPLE :( 10) calculate molarity of 44.8 V strength of 
H2O2 aq Solution?.
EXAMPLE: (11) calculate the molarity of H2O2 if 11.2 ml H2O2 require 30 ml of 0.5 M K2Cr2O7 for its complete oxidation; also calculate the Volume strength of H2O2? (Ans M=45/11.2 and volume strength=45)

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