TAS - order of reaction decomposition of hydrogen peroxide

natsu

2007-01-16 8:20 am

potassium manganate(VII), hydrogen peroxide are reacting in a conical flask. At different time intervals, 10cm3 of reaction mixture is withdrawn, add to conical flask with 10cm3 H2SO4(stopwatch is started at this instant) and is then titrated with dilute K2MnO4 solution.
Q.1 what is the use of the dilute sulphuric acid? (quench reaction?provide H+ for the titration?)
Q.2 Why the time is taken when dilute sulphuric acid is added?

更新1:

Q.3 At different time intervals, amount of hydrogen peroxide left in the reaction mixture is determined by titrating with standard potassium manganate(VII) in acidic medium. Write an equation for the reaction in the titration.

更新2:

May I ask one more question? Then, how does the sulphuric acid quench the reaction? If there's an equation, please give me !!

更新3:

Ya, because the menu says manganese permanganate is reduced by some of the hydrogen peroxide to MnO2 for the decomposition of H2O2.

回答 (2)

[匿名]

2007-01-18 10:05 am

✔ 最佳答案

(我用中文考，英文不是很好，所以有些字寫了中文)
Q1
the use of the dilute sulphuric acid is to provide H+ for the reaction

Q2
把第一個titration所測到的H2O2數量當作最開始的數量
(因為H2O2會愈來愈少，把這個數與之後titrate得到的H2O2 volume相減，就可以得出一個time interval H2O2 decomposite左幾多)

Q3
7e- + 10H+ + MnO4- + H2O2 --> Mn2+ + 6H20

2007-01-19 01:16:06 補充：
sulphuric acid用來quench H2O2的decomposition，因為sulphuric acid provide H+ for以下的reaction5H2O2 + 2MnO4- + 6H+ -> 2Mn2+ + 8H2O + 5O2 (上面果條錯左,sorry)一加入sulphuric acid，反應就會開始

2007-01-19 01:17:21 補充：
題目真是寫potassium manganate(VII), hydrogen peroxide are reacting in a conical flask.?因為我看書是寫manganese(IV) oxide as catalyst

參考: me

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Sky

2007-03-15 5:21 am

改完都係錯

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