Question

Several aqueous solutions were added together creating a mix of ions. For each of the mixtures, predict if there will any insoluble ionic compounds (precipitate) produced? Circle YES or NO If yes, write down the molecular formula of the precipitate, If no, write NO REACTION

If a precipitate formed, write down the molecular formula of the precipitate, If no, write down “no reaction”

1, NH4 + (aq), K + (aq), CO3 2- (aq), F - (aq), PO4 3- (aq)

2. Na+ (aq), Pb2+ (aq), Al3+(aq), Cl- (aq), NO3 - (aq)

Insoluble product(s)? yes or no

Answer 1

1. We know that all ammonium (having cation NH4+) and potassium (having cation K+) salts are soluble in water. Here we have only potassium ion and ammonium ion as the cation (positive ion), rest are anions (negative ions). So none of these combinations is insoluble. The combination of given anions (F-, CO32- and PO43-) will form soluble salts with K+ and NH4+. Answer is No Reaction.

2. We know that all sodium salts (having Na+ cation) and nitrates (having NO3- as anion) are soluble. So combination of Na+ with any anion and combination of any cation with NO3- is soluble. Chlorides of all metals are soluble except that of lead (Pb), mercury and silver. Combination of Cl- with given cations will be soluble except with Pb2+. So PbCl2 (formula of precipitate formed) will be insoluble. i.e. combination of Pb2+ with 2 Cl- (as +2 charge of Pb2+ will be balanced by -1 negative charge of two Cl-) will be insoluble and will form a precipitate.

So YES the reaction takes place and precipitate formed is PbCl2.