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# Redox equation what has gone wrong? watch

1. The reduction of chlorate(V) ions, ClO3 - , to chlorine gas, Cl2. I have to construct a half equation for this.
My answer : 10e- + 2ClO3- + 6H+ --> Cl2 +6OH- I have checked this and the charges do balance..

ANSWER 2ClO3 - + 12H+ + 10e- -> Cl2 + 6H2O

The answer shows water is made but I thought OH- would, am I wrong. But if the charges are balanced then would it be okay? I don't know whether my equation makes sense...

Thanks
2. Help?
3. (Original post by coconut64)
The reduction of chlorate(V) ions, ClO3 - , to chlorine gas, Cl2. I have to construct a half equation for this.
My answer : 10e- + 2ClO3- + 6H+ --> Cl2 +6OH- I have checked this and the charges do balance..

ANSWER 2ClO3 - + 12H+ + 10e- -> Cl2 + 6H2O

The answer shows water is made but I thought OH- would, am I wrong. But if the charges are balanced then would it be okay? I don't know whether my equation makes sense...

Thanks
Does the question specify that it's being done under acidic conditions? If so, you can't add hydroxide ions as they will neutralise the H+ ions.

Can you put up the Oxidation half equation also?
4. (Original post by _NMcC_)
Does the question specify that it's being done under acidic conditions? If so, you can't add hydroxide ions as they will neutralise the H+ ions.
No, it is just asking to show an equation for it. It is not an exam question. My equation is balanced, so does it matter ?

Thanks
5. in acidic conditions hydroxide ions are never on either side of the equation
6. (Original post by _NMcC_)
Does the question specify that it's being done under acidic conditions? If so, you can't add hydroxide ions as they will neutralise the H+ ions.

Can you put up the Oxidation half equation also?

can't add hydroxide ions as they will neutralise the H+ ions. -> but if you take H2O2 as an example, there are both H+ and OH- in the equation
7. (Original post by coconut64)
No, it is just asking to show an equation for it. It is not an exam question. My equation is balanced, so does it matter ?

Thanks
It's probably not worth many marks anyway but unless it specifies or it's obvious that an alkaline solution is being formed. I usually always balance for acidic conditions.
8. (Original post by Student1256)
in acidic conditions hydroxide ions are never on either side of the equation
So are you suggesting that if I have H+ on the reactant side, no OH- will be made
If I have OH- on the reactant side, no H+ is made?

Thanks
9. (Original post by coconut64)
The reduction of chlorate(V) ions, ClO3 - , to chlorine gas, Cl2. I have to construct a half equation for this.
My answer : 10e- + 2ClO3- + 6H+ --> Cl2 +6OH- I have checked this and the charges do balance..

ANSWER 2ClO3 - + 12H+ + 10e- -> Cl2 + 6H2O

The answer shows water is made but I thought OH- would, am I wrong. But if the charges are balanced then would it be okay? I don't know whether my equation makes sense...

Thanks
ASSUMING ACIDIC CONDITIONS
Start: ClO3- -> Cl2
1) Balance Cl
2ClO3- -> Cl2
2) Balance Oxygen with water
2ClO3- -> Cl2 + 6H20
3) Balance Hydrogen with H+
12H+ + 2ClO3- -> Cl2 + 6H20
4) Balance charge with electrons
10e- + 12H+ + 2ClO3- -> Cl2 + 6H20, as given.
10. (Original post by britishtf2)
ASSUMING ACIDIC CONDITIONS
Start: ClO3- -> Cl2
1) Balance Cl
2ClO3- -> Cl2
2) Balance Oxygen with water
2ClO3- -> Cl2 + 6H20
3) Balance Hydrogen with H+
12H+ + 2ClO3- -> Cl2 + 6H20
4) Balance charge with electrons
10e- + 12H+ + 2ClO3- -> Cl2 + 6H20, as given.
How can you predict H2O is formed, I balanced my equation using OH- ions and the charges do balance too
11. (Original post by coconut64)
can't add hydroxide ions as they will neutralise the H+ ions. -> but if you take H2O2 as an example, there are both H+ and OH- in the equation
Look at the example on this page by Jim Clark, you can balance redox half equations involving H202 using H20 and H+ ions.

http://www.chemguide.co.uk/inorganic...equations.html
12. (Original post by coconut64)
How can you predict H2O is formed, I balanced my equation using OH- ions and the charges do balance too
By assuming acidic conditions, i.e. presence of H+ [as you see on the LHS], OH- are neutralised by the H+, making water.
13. (Original post by coconut64)
So are you suggesting that if I have H+ on the reactant side, no OH- will be made
If I have OH- on the reactant side, no H+ is made?

Thanks
Yes, under alkaline conditions, OH- is involved - balance with H20
Under acidic consitions, H+ is involved - balance with H20

H+ and OH- are never usually used to balance each other in redox equations.
14. Thanks for the help, I get it now
15. (Original post by coconut64)
Thanks for the help, I get it now
No problem, glad to help.
16. (Original post by coconut64)
Thanks for the help, I get it now
np, just practice and you'l be fine.

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