Precipitates and Solubility

 You already know that certain elements are more reactive than others due to size, number of valence electrons, ionization energies, and electronegativities. Many substances split into positive and negative ions when dissolved in water (i.e., soluble). Sometimes the positive ion from one compound will recombine with the negative ion of the second compound and settle to the bottom of the container (i.e., precipitate). The other ions may stay in solution. Use the following solubility rules to help you identify what products may be formed that precipitate out of solution in the reactions that follow.

 Solubility Rules (in water solutions)

1. All common salts of the alkali elements (Group 1) and ammonium ion are soluble.

2. All common acetates and nitrates are soluble.

3. All binary compounds of the halogens (Group 17), other than fluorine, with metals are soluble except those of silver, mercury (I), and lead.

4. All sulfates are soluble except those of barium, strontium, lead, calcium, silver, and mercury (I).

5. Except for those in Rule 1, carbonates, hydroxides, oxides, and phosphates are insoluble.

 Instructions: Fill out the products of the following double replacement reactions and try to identify which will be a precipitate and which will be soluble. Also balance the equations.

 1.         barium chloride + manganese (II) sulfate -->

2.         sodium chloride + potassium iodide -->

3.         copper (II) sulfate + sodium hydroxide -->

4.         iron (III) chloride + sodium hydroxide -->

5.         lead (II) nitrate + manganese (II) sulfate -->

6.         lead (II) nitrate + potassium iodide -->

7.         sodium carbonate + potassium iodide -->

8.         sodium carbonate + barium chloride -->

9.         lead (II) nitrate + potassium chromate -->

10.       copper (II) sulfate + sodium chloride -->

11.       copper (II) sulfate + sodium carbonate -->

12.       potassium iodide + sodium hydroxide -->