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Redox equation what has gone wrong? Watch

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    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
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    (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?
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    (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 ?

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    in acidic conditions hydroxide ions are never on either side of the equation
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    (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
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    (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 ?

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    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.
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    (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?

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    (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.
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    (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
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    (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
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    (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.
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    (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.
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    Thanks for the help, I get it now
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    (Original post by coconut64)
    Thanks for the help, I get it now
    No problem, glad to help.
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    (Original post by coconut64)
    Thanks for the help, I get it now
    np, just practice and you'l be fine.
 
 
 
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