Redox reactions

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Dhamnekar Winod
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Redox reactions

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How to answer all these following questions?

I am working on these questions. If you know the answers to these questions, you may post them. Why can't i paste the screenshot copied on clipboard here?
electrontransfer reaction.png
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Any science consists of the following process. 1) See 2)Hear 3)Smell,if needed 4)Taste, if needed 5)Think 6)Understand 7)Inference 8)Take decision [Believe or disbelieve, useful or useless, true or false, cause or effect, any other criteria]
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Re: Redox reactions

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For redox reaction use the redox pair law
a) S2O3 2- / S4O6 2- and I2/I-

2 S2O3 2- => S4O6 2-

Balance charge
2 S2O3 2- => S4O6 2- + 2e-

I2 => 2 I-

Balance charge
I2 + 2e- => 2 I-

Addition

2 S2O3 2- + I2=> S4O6 2- + 2 I-
Try the other by yourself.
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Re: Redox reactions

Post by Dhamnekar Winod »

Answers to a), b) , C).
RR123.png
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Re: Redox reactions

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The final results are ok, I am wondering where the 2 H+ + 2e- comming from. Especially there is no acid in 1. and 2.

Fe 2+ => Fe 3+ + e- Oxidation
Ce 4+ +e - => Ce 3+ Reduction
Fe 2+ + Ce 4+ => Fe 3+ + Ce 3+ Addition
Sulfate is spectator ion
For completion multiply by 2 and add SO4 2-
2 FeSO4 + 2 Ce(SO4)2 => Fe2(SO4)3 + Ce2(SO4)3

Fe 2+ => Fe 3+ + e- Oxidation

HNO3 + 3 H+ + 3e- => 2 H2O + NO Reduction

Multiplikation of Oxidation by 3
3 Fe 2+ + 3 Fe 3+ + 3 e-

3 Fe 2+ + HNO3 + 3 H+ => 3 Fe 3+ + 2H2O + NO Addition
Also hier sulfate is spectator but can be added accordingly

6 FeSO4 + 2HNO3 + 3 H2SO4 => 3 Fe2(SO4)3 + 4 H2O + 2 NO
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Re: Redox reactions

Post by Dhamnekar Winod »

Answers to d), e), f), g).
RRdefg.png
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Re: Redox reactions

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I dont understand how you develop the part equations. In e) for example you use OH- even the reaction takes place with HCl. With mathematics a lot can do even the final result is correct but generally its wrong.

To start like this

d) S 2- => S + 2 e- Oxidation
HNO3 + 3 H+ +3 e- => NO + 2 H2O Reduction

e) S 2- => S+ 2 e- Oxidation
Cr2O7 2- + 6 HCl + 8 H+ + 6 e- => 2 Cr 3+ + 7 H2O + 6 Cl- Reduction

f) Cl2 + 12 OH- => 2 ClO3- + 6 H2O + 10 e- Oxidation
Cl2 + 2 e- => 2 Cl- Reduction

g) Fe 2+ => Fe 3+ + e- Oxidation

O2 2- + 2H2O + 2 e- => 4 OH- Reduction
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Re: Redox reactions

Post by Dhamnekar Winod »

In answer to e) , I used basic medium even though HCl is reactant. You said it is wrong. After using acidic medium, the answer is as follows:
RRehij.png
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The balanced net ionic equations for h), i), j) are as follows:
h)\(Bi_2S_3 + 8HNO_3 \rightleftarrows 2Bi(NO_3)_3 + 2NO + 3S + 4H_2O\)

i)\(H_3AsO_4 + 4Zn + 8HNO_3 \rightleftarrows AsH_3 + 4Zn(NO_3)_2 + 4H_2O\)

j)\(2CrI_3 + 64NaOH + 27Cl_2 \rightleftarrows 2Na_2CrO_4 + 6NaIO_4 + 54NaCl + 32H_2O\)
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