Author Topic: Is the following solution correct? Redox question. (Read 1983 times) Tweet Share

dekoyl · « **on:** February 21, 2009, 10:26:18 pm »

I think it's wrong (both in the book and in worked-through electronic form). I think there should've been a 2 in front of the $MnO_2$ .

It might be very obvious but I'm not confident enough in chemistry to decide for myself (still re-learning unit 2 stuff :S)

Thanks

Edit: Oops. Original question was:
$MnO_2(s) + H^{+}(aq) + S(s) \rightarrow Mn^{2+}(aq) + H_2O(l) + SO_2(g)$

shinny · « **Reply #1 on:** February 21, 2009, 10:32:10 pm »

Yep there's meant to be a 2 there from what I see at first glance.

Mao · « **Reply #2 on:** February 21, 2009, 11:13:28 pm »

looks like everything's unbalanced, here's what they should be

$MnO_2 (s) + 4H^+(aq) + 2e^- \to Mn^{2+}(aq) + 2H_2O(l)$

$S (s) + 2H_2O(l) \to SO_2 (g) + 4H^+(aq) + 4e^-$

$2MnO_2 (s) + S (s) + 4H^+ (aq) \to 2Mn^{2+}(aq) + SO_2(g) + 2H_2O(l)$

dekoyl · « **Reply #3 on:** February 22, 2009, 02:51:15 pm »

^ Thanks Shinny and Mao :]

Gosh another one (I think?).

Iron content in a 0.2g sample of fencing wire was determined by dissolving the wire in dilute H2SO4 and making up the resulting pale green solution of Fe2+ ions to 25mL.
Fe2+ titrated with KMnO4. Solution of Mn2+ and Fe3+ is produced.
The final equation from answers is :
$5Fe^{2+}(aq) + KmNO_4(aq)+8H^{+}(aq) \rightarrow 5Fe^{3+}(aq) + Mn^{2+}(aq) + 4H_2O(l)$

Is that correct? I got 6 instead of fives infront of Fe

$T^{h^{a^{n^{k^{s^{s^{s^{s^{s}}}}}}}}}}}}}$

d0minicz · « **Reply #4 on:** February 22, 2009, 03:11:04 pm »

I got the same as you

khalil · « **Reply #5 on:** February 26, 2009, 07:30:32 pm »

can someone help me with this one?
what volume of .0823M KMnO(4) is needed to oxidise 2.5g of anhydrous iron(II) sulfate to iron (III) sulfate in acid solution?
I dont understand y in the answers they oxidise MnO(4)- to Mn^2+

Mao · « **Reply #6 on:** February 26, 2009, 09:19:26 pm »

$MnO_4^-$ is reduced to $Mn^{2+}$ , the oxidation number of manganese is +7 --> +2

khalil · « **Reply #7 on:** February 26, 2009, 09:39:43 pm »

ok but where did they pull Mn^2+ from?

Mao · « **Reply #8 on:** February 27, 2009, 12:21:29 am »

that's what it generally gets reduced to.

khalil · « **Reply #9 on:** February 27, 2009, 04:56:25 pm »

so its a set. concrete rule?

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Author Topic: Is the following solution correct? Redox question. (Read 1983 times) Tweet Share

dekoyl

Is the following solution correct? Redox question.

shinny

Re: Is the following solution correct? Redox question.

Mao

Re: Is the following solution correct? Redox question.

dekoyl

Re: Is the following solution correct? Redox question.

d0minicz

Re: Is the following solution correct? Redox question.

khalil

Re: Is the following solution correct? Redox question.

Mao

Re: Is the following solution correct? Redox question.

khalil

Re: Is the following solution correct? Redox question.

Mao

Re: Is the following solution correct? Redox question.

khalil

Re: Is the following solution correct? Redox question.

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