PowerPuff
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What's the difference between...

  • Ionic Equations
  • Simplest Ionic Equations: Example – When acidified barium chloride is added to sulfate ions?
  • Half Equations
  • Reduction/Oxidation Equations (separately not as redox)



If you could include examples/answers for the other forms of equations, that would be awesome

(AS Chemistry)
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EierVonSatan
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There's only two types here ionic and half equations. Redox equations can be split into oxidation and reductions, which are both half equations.

Ionic equations leave out parts of molecules that don't take part in the reaction (called spectator ions) your example:

BaCl2(aq) + H2SO4(aq) ----> 2HCl(aq) + BaSO4(s) is the full equation

by 1) splitting up the aqueous parts in ions then 2) removing ions that appear on both sides you end up with the ionic equation:

Ba2+(aq) + SO2-4(aq) ---> BaSO4(s)

Half equations show either reduction or oxidation (you can tell if something is a half equation if it has electrons in it), for example:

Fe2+ ----> Fe3+ + e-

represents the half equation for the oxidation of iron(II) to iron(III).
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PowerPuff
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(Original post by EierVonSatan)
There's only two types here ionic and half equations. Redox equations can be split into oxidation and reductions, which are both half equations.

Ionic equations leave out parts of molecules that don't take part in the reaction (called spectator ions) your example:

BaCl2(aq) + H2SO4(aq) ----> 2HCl(aq) + BaSO4(s) is the full equation

by 1) splitting up the aqueous parts in ions then 2) removing ions that appear on both sides you end up with the ionic equation:

Ba2+(aq) + SO2-4(aq) ---> BaSO4(s)

Half equations show either reduction or oxidation (you can tell if something is a half equation if it has electrons in it), for example:

Fe2+ ----> Fe3+ + e-

represents the half equation for the oxidation of iron(II) to iron(III).
Thank you.

what about when your adding up half equations?
should it show a redox reaction including h+ e- ect or look like a normal equation.
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EierVonSatan
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(Original post by PowerPuff)
Thank you.

what about when your adding up half equations?
should it show a redox reaction including h+ e- ect or look like a normal equation.
When you're adding two half equations together to get a full equation, the number of electrons must match for both. So imagine:

Fe2+ ----> Fe3+ + e-

MnO4- + 8H+ + 5e- ---> Mn2+ + 4H2O

the oxidation has 1 electron, the reduction has 5 electrons. Need to multiply the whole oxidation half equation by 5 to make it the same.

5Fe2+ ----> 5Fe3+ + 5e-

MnO4- + 8H+ + 5e- ---> Mn2+ + 4H2O

combining them:

MnO4- + 8H+ + 5Fe2+ ---> Mn2+ + 4H2O + 5Fe3+
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PowerPuff
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(Original post by EierVonSatan)
When you're adding two half equations together to get a full equation, the number of electrons must match for both. So imagine:

Fe2+ ----> Fe3+ + e-

MnO4- + 8H+ + 5e- ---> Mn2+ + 4H2O

the oxidation has 1 electron, the reduction has 5 electrons. Need to multiply the whole oxidation half equation by 5 to make it the same.

5Fe2+ ----> 5Fe3+ + 5e-

MnO4- + 8H+ + 5e- ---> Mn2+ + 4H2O

combining them:

MnO4- + 8H+ + 5Fe2+ ---> Mn2+ + 4H2O + 5Fe3+
Thank you (even though I knew how to do it before)
Just there was a question which showed half equations then said

now dedude the full ionic equation...
and I was confused whether they were asking for the completed redox equation or the actual ionic equation for the reaction
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EierVonSatan
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(Original post by PowerPuff)
Thank you (even though I knew how to do it before)
Just there was a question which showed half equations then said

now dedude the full ionic equation...
and I was confused whether they were asking for the completed redox equation or the actual ionic equation for the reaction
The last equation I gave in my last post was the ionic equation from the two half equations

The full equation would be KMnO4 sulfuric acid etc
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PowerPuff
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(Original post by EierVonSatan)
The last equation I gave in my last post was the ionic equation from the two half equations

The full equation would be KMnO4 sulfuric acid etc
I didnt now ionic equations included eletrons on its own...
I thought that was only for half equations so confused :confused:
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TheGrinningSkull
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(Original post by PowerPuff)
I didnt now ionic equations included eletrons on its own...
I thought that was only for half equations so confused :confused:
When you combine the half equations, the electrons should chancel and you should get a redox/ionic equation.

The last equation mentioned by EierVonSatan shows no electrons:

5Fe2+ ----> 5Fe3+ + 5e-

MnO4- + 8H+ + 5e- ---> Mn2+ + 4H2O

combining them:

MnO4- + 8H+ + 5Fe2+ ---> Mn2+ + 4H2O + 5Fe3+
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edudog
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Why is this a half equation: Li^+ + MnO2 + e^- -> LiMnO2
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edudog
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I do not understand why the following is considered a half equation:
Li^+ + MnO2 + e- -> LiMnO2

Half equations would usually be more like:
Li^+ + e- -> Li

and the general rule is that only H+ ions, water and electrons can be added, so why is the above equation a half equation? (My CGP revision guide implies it is a half equation)
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charco
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(Original post by edudog)
I do not understand why the following is considered a half equation:
Li^+ + MnO2 + e- -> LiMnO2

Half equations would usually be more like:
Li^+ + e- -> Li

and the general rule is that only H+ ions, water and electrons can be added, so why is the above equation a half equation? (My CGP revision guide implies it is a half equation)
It is a half-equation as it only shows the reduction part of a redox process...
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edudog
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(Original post by charco)
It is a half-equation as it only shows the reduction part of a redox process...
The following equation only shows oxidation, yet my revision guide does not classify it as a half equation:
2MnO2 +2NH4^+ +2e^- ->Mn2O3 +2NH3 +H20
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charco
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(Original post by edudog)
The following equation only shows oxidation, yet my revision guide does not classify it as a half equation:
2MnO2 +2NH4^+ +2e^- ->Mn2O3 +2NH3 +H20
This is also a reduction half-equation ..

.. addition of electrons = reduction.

Manganese changes oxidation state from +4 to +3
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edudog
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(Original post by charco)
This is also a reduction half-equation ..

.. addition of electrons = reduction.

Manganese changes oxidation state from +4 to +3
But the NH4+ loses a hydrogen ion to become NH3, and that's oxidation, right? So wouldn't the equation be showing both in that case?
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charco
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(Original post by edudog)
But the NH4+ loses a hydrogen ion to become NH3, and that's oxidation, right? So wouldn't the equation be showing both in that case?
No, the ammonium ion loses a hydrogen ion. This is not oxidation or reduction, there are no change in oxidation states ...

N = -3 before and after
H = +1 before and after
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edudog
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(Original post by charco)
No, the ammonium ion loses a hydrogen ion. This is not oxidation or reduction, there are no change in oxidation states ...

N = -3 before and after
H = +1 before and after
So would the MnO2 turning to Mn2O3 be the oxidation part of the reaction? Or is there another part which is the oxidation.
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charco
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(Original post by edudog)
So would the MnO2 turning to Mn2O3 be the oxidation part of the reaction? Or is there another part which is the oxidation.
manganese(IV) oxide turning to manganse(III) oxide is reduction ....

there is no oxidation, that's why it's a half-equation.
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edudog
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(Original post by charco)
manganese(IV) oxide turning to manganse(III) oxide is reduction ....

there is no oxidation, that's why it's a half-equation.
Makes sense, thanks for helping me out!
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