Preciptation(Molecular Equation and net ionic equation)

[Susanem7389]

Write the molecular eqaution and the net ionic equation for each of the following aqueous reactions. If no reaction occurs, write NR after the arrow.

A) Na2Co3 + MgBr2--->
B)MgSO4 + NaOH---->

I can't figure these two out. From the solubility rules, all the compounds are soluble so there shouldn't be a reation but the answer in the back of the book shows a reaction.

What am I doing wrong?

 

[Borek]

Solubility is not 0/1 - substance is either soluble or insoluble. All salts are soluble, just some more and some less. Depending on where do you put the border between those that will be classified as soluble and insoluble rules will be slightly different.

However, there are two weakly soluble products of these reactions - two that I beleve should be listed in most solubility rules tables.

 

[Blueshift5]

Molecular equation for A: Na2CO3 + MgBr2 --> 2NaBr + MgCO3

Net ionic equation for A: 2Na+ + CO3^2- + Mg2+ + 2Br- --> 2Na+ + 2Br- + MgCO3 (s)

Molecular equation for B: MgSO4 + 2NaOH --> Mg(OH)2 + Na2SO4

Net ionic equation for B: Mg2+ + SO4^2- + 2Na+ + 2OH- --> Mg(OH)2 (s) + 2Na+ + SO4^2-

Based on the solubility rules, both of these reactions should not occur because all of the compounds are soluble. However, it is possible that the reaction in the book is a precipitation reaction that is not accounted for by the solubility rules. It is also possible that there is a typo in the book. I would recommend double checking the information and possibly consulting with a chemistry colleague or instructor for clarification.