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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: joe900 on April 11, 2015, 03:00:43 PM

Title: bromate, iodate and chlorate...
Post by: joe900 on April 11, 2015, 03:00:43 PM: Could you please tell me, if THERE REACTIONS ARE CORRECT?

1) preparation of sodium chlorate :
NaCl + 3H2O = NaClO3 + 3H2

2) preparation of potassium chlorate from sodium chlorate:
NaClo3 + KCl = NaCl + KClO3

3) how to prepare

A. barium chlorate:
BaO +Cl2O5 = BaCl2O6

B.nickel chlorate:
have no idea :(

4) methods of preparation of any bromate, iodate and compare it with chlorate:

e.g.
6 NaOH (hot) + 3Br2 = NaBrO3 + 5 NaBr + 3H2O

NaI + 3H2O = electrolysis 3H2 (cathode) + NaIO3 (anode)

NaCl + 3H2O = NaClO3 + 3H2

how to compare methods of preparation this compounds?
and what are the differemces in reactivity of products: bromate, iodate and chlorate?

5) how to prepare KIO3 from Cl2, KI and K2CO3:

2KI + Cl2 = 2KCl + I2
3K2CO3 + 3 H2O + 3I2 = KIO3 + 5 KI +3H2CO3

THANKS IN ADVANCE!!
Title: Re: bromate, iodate and chlorate...
Post by: Arkcon on April 11, 2015, 03:41:21 PM: Quote from: caro900 on April 11, 2015, 03:00:43 PM
Could you please tell me, if THERE REACTIONS ARE CORRECT?

1) preparation of sodium chlorate :
NaCl + 3H2O = NaClO3 + 3H2

OK, this one is simply ridiculous. You've simply balanced the atoms, but this reaction simply won't go forward. Table salt dissolves in water, it doesn't become a highly energetic, oxidizing compound.
Title: Re: bromate, iodate and chlorate...
Post by: joe900 on April 11, 2015, 03:46:53 PM: I have found it in literature:

"Industrially, sodium chlorate is produced by the electrolysis of a hot sodium chloride solution:
NaCl + 3 H2O → NaClO3 + 3 H2
This reaction progresses in heat (at least 70 degrees Celsius), and controlled pH."
Title: Re: bromate, iodate and chlorate...
Post by: Arkcon on April 11, 2015, 06:50:26 PM: Ah. But you did leave out the electricity driving the reaction that you wanted, didn't you?
Title: Re: bromate, iodate and chlorate...
Post by: unsu on April 12, 2015, 12:15:22 AM: Quote
1) preparation of sodium chlorate :
NaCl + 3H2O = NaClO3 + 3H2
Here you forgot to specify the conditions: electrolysis without diaphragm

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2) preparation of potassium chlorate from sodium chlorate:
NaClO3 + KCl = NaCl + KClO3
Yes, this is possible because KClO3 is much less soluble in water than NaClO3

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3) how to prepare
A. barium chlorate:
B.nickel chlorate:
It can be prepared from barium chloride (common reagent) and NaClO3 (produced industrially in large scale):
BaCl2 + 2NaClO3 = 2NaCl + Ba(ClO3)2
Barium chlorate can be crystallized from solution.
For nickel(II) chlorate I would suggest similar reaction.

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4) methods of preparation of any bromate, iodate and compare it with chlorate:

KClO3 can be prepared by 1) reaction between NaClO3 and KCl; 2) by passing Cl2 gas through hot KOH solution; 3) by electrolysis of aqueous KCl without diaphragm

KBrO3 can also be prepared by 1) reaction Br2 + KOH (or K2CO3) = KBrO3 + KBr + H2O
2) electrolysis aqueous KBr without diaphragm; 3) by reaction of Br2 with excess Cl2 in KOH:
Br2 + 5Cl2 + 12KOH = 2KBrO3 + 10KCl + 6H2O (80 °C)

KIO3 can be prepared from KI:
electrolysis of aqueous KI without diaphragm: KI + 3H2O = KIO3 + 3H2
or by reaction between KI and KClO3: KI + KClO3 = KIO3 + KCl
or oxidation with excess chlorine:
KI + 3Cl2(excess) + 6KOH = KIO3 + 6KCl + 3H2O
(KIO3 can be isolated by crystallization)
or from 3I2 + 6KOH = KIO3 + 5KI + 3H2O

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and what are the differemces in reactivity of products: bromate, iodate and chlorate?
Analyze the Frost diagrams for halogens and compare standard reduction potentials for XO₃^-/X₂. For Cl, Br and I the values of E° are 1.468, 1.478 and 1.195 V respectively.
The oxidizing ability of XO₃^- is decreasing in order: BrO₃^- ≈ ClO₃^- > IO₃^-. The bromates are the strongest oxidizing agents.
2KBrO3 + I2 = 2KIO3 + Br2
2KBrO3 + Cl2 = 2KClO3 + Br2
2KClO3 + I2 = 2KIO3 + Cl2

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5) how to prepare KIO3 from Cl2, KI and K2CO3:
Chlorine liberates I2 from KI and then it oxidizes I2 to iodate:
2KI + Cl2 = I2 + 2KCl
Cl2(excess) + I2 + 12K2CO3 + 6H2O = 2KIO3 + 10KCl + 12KHCO3

PS electrolysis with diaphragm would give you a regular chloralkali process, where NaOH is produced and it does not come into contact with Cl2 gas, so there is no reaction between NaOH and Cl2 to produce NaClO3
Title: Re: bromate, iodate and chlorate...
Post by: snorkack on May 03, 2015, 12:48:09 PM: Quote from: unsu on April 12, 2015, 12:15:22 AM
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3) how to prepare
A. barium chlorate:
B.nickel chlorate:
It can be prepared from barium chloride (common reagent) and NaClO3 (produced industrially in large scale):
BaCl2 + 2NaClO3 = 2NaCl + Ba(ClO3)2
Barium chlorate can be crystallized from solution.
For nickel(II) chlorate I would suggest similar reaction.
But this depends on the specifics of solubility of nickel chlorate, the nickel salt used and the corresponding sodium salt.
A problem with using sodium salts to produce other salts is that sodium has few poorly soluble salts to drive formation of the desired salts.