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How do I write the formulae of the ions produced when these compounds dissolve in...

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lilian-0716 | Student | Salutatorian

Posted July 21, 2013 at 4:14 AM via web

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How do I write the formulae of the ions produced when these compounds dissolve in water?

Magnesium hydrogen carbonate

Calcium nitrate

Potassium hydrogen sulphate

Iron (III) sulphate

Copper (II) chloride

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llltkl | College Teacher | Valedictorian

Posted July 21, 2013 at 5:00 AM (Answer #1)

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When ionic compounds come in contact with water,  they dissociate into their constituent ions. Opposite poles of water molecule then surround each type of ions, thereby giving them sufficient stability in the ionic state. This process is called solvation (hydration, when the solvent is water) of ions, and represented as M+(aq.) or K-(aq.).

The given compounds will dissociate in aqueous solution as follows:

`MgHCO_3 +H_2O stackrel larr rarr Mg^(2+)(aq.)+HCO_3^(-)(aq.)`

and again, `HCO_3^(-)(aq.) stackrel larr rarr H^+(aq.) + CO_3^(2-)(aq.)`

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Overall `MgHCO_3 +H_2O stackrel larr rarr Mg^(2+)(aq.)+H^+(aq.)+CO_3^(2-)(aq.)`

`Ca(NO_3)_2+H_2O stackrel larr rarr Ca^(2+)(aq.) + 2NO_3^(-)(aq.)`

`KHSO_4 +H_2O stackrel larr rarr K^+(aq.)+ HSO_4^(-)(aq.)`

and again, `HSO_4^(-)(aq.) stackrel larr rarr H^+(aq.) + SO_4^(2-)(aq.)`

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`KHSO_4 +H_2O stackrel larr rarr K^+(aq.)+ H^++SO_4^(2-)(aq.)`

`Fe_2(SO_4)_3 +H_2O stackrel larr rarr 2Fe^(3+)(aq.) + 3SO_4^(2-)(aq.)`

`CuCl_2 + H_2O stackrel larr rarr Cu^2+(aq.) + 2Cl-(aq.)`

Sources:

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lilian-0716 | Student | Salutatorian

Posted July 21, 2013 at 9:03 AM (Answer #2)

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thanks :)

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llltkl | College Teacher | Valedictorian

Posted July 21, 2013 at 12:33 PM (Reply #1)

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There is another convention to write dissolutions in which water is not included in the reaction, i.e.

`CuCl_2(s) stackrel (H_2O) rarr Cu^(2+)(aq.) and 2Cl^(-)(aq.)`

Yet another area of argument is dissociation of bi-salts. Thus, some people prefer dissociation of `KHSO_4` to be stopped in the first step.

`KHSO_4(s) stackrel (H_2O) rarr K^(+)(aq.)+HSO4^(-)(aq.)`

 

 

 

 

 

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