[Catalist] One for the Chemists

[Ann Moseley]

I thought the same! I couldn't see redox titrations anywhere?!

On 4 March 2016 at 11:32, de la Haye, Maya <
delahaye.maya at cathednet.wa.edu.au> wrote:

> Correct me if I am wrong but I thought redox titrations were out of the
> new curriculum?
> Maya
>
> Sent from my iPhone
>
> On 3 Mar 2016, at 4:31 PM, Andrew Bland <abl at gmas.wa.edu.au> wrote:
>
> Hi all, please check if you agree with this model answer, from a
> validation after a redox titration, permanganate + hydrogen peroxide.
> Thanks, Andrew.
>
>
>
> Q: If insufficient acid is added in step 9, some of the permanganate ions
> will react to form MnO2 instead of Mn2+. The equation for this reaction
> is:
>
>
>
>                                             2 MnO4- + 3H2O2 + 2H+  à 2MnO2
> + 4H2O +3O2
>
> The original equation is:
>
>                             2MnO4- + 5H2O2 + 6H+ à 5O2 + 2Mn2+ +8 H2O
>
>
>
>
>
> a. How would this affect the volume of KMnO4 used to reach the end point?
> (Would it be more or less). Explain why.
>
>
>
> A: In the original reaction, 2 mol of MnO4- will react with 5 mol of H2O2.
> In the new reaction, 2 mol of MnO4- will react with 3 mol of H2O2, meaning
> that more MnO4- would be required to react with the same amount of H2O2 to
> reach the end point.
>
> The result would be that the concentration of H2O2 would be over
> estimated.
>
>
> Andrew Bland
> Teacher
> T:  +61 8 9752 5252
> F:  +61 8 9752 5299
> E:  abl at gmas.wa.edu.au
> W: www.gmas.wa.edu.au
> <gmas_8d303a86-5e08-4291-93c0-5df048a26040.jpg>
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-- 
*Ann Moseley*
Year 7 Manager | Carey Baptist College
*P *08 9394 9111 *F* 08 9394 9112 *W* carey.wa.edu.au
51 Wright Rd Harrisdale WA 6112. PO Box 1409 Canning Vale WA 6970.

*Carey *Attempt the Extraordinary


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