1) preparation of sodium chlorate :
NaCl + 3H2O = NaClO3 + 3H2
Here you forgot to specify the conditions:
electrolysis without diaphragm 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
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.
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
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 XO
3-/X
2. For Cl, Br and I the values of E° are 1.468, 1.478 and 1.195 V respectively.
The oxidizing ability of XO
3- is decreasing in order: BrO
3- ≈ ClO
3- > IO
3-. The bromates are the strongest oxidizing agents.
2KBrO3 + I2 = 2KIO3 + Br2
2KBrO3 + Cl2 = 2KClO3 + Br2
2KClO3 + I2 = 2KIO3 + Cl2
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