Question

only one of each of the following pairs of reactants undergoes a reaction. Complete and balance the equation for the reaction that occurs.

NaCl (aq) + BaCl2 (aq) -->
Na2SO4 (aq) + BaCl2 (aq) -->

NO3^- (aq) + OH^- (aq)+ Al (s) -->
CO3^2- (aq) + OH^- (aq) +Al (s) -->

K^+ (aq) + Cl^- (aq) -->
Ag^+ (aq) + Cl^- (aq) -->

can you also explain WHY the one pair undergoes a reaction? Thanks so much!!

Answer 1

The first pair:
You look at the table of solubilities.
Reactions occur for three primary reasons.
a. an insoluble ppt formed.
b. a gas formd
c. a weak electrolyte formed.
Here is a simplified table of solubilities.
http://www.files.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html
For the first pair you will note BaSO4 is not soluble.
Third pair: AgCl is insoluble.
Second pair: I think someone goofed. Both equations will go because Al + OH^- gives H2 + Al(OH)3.