Question

Cold water is added to each of the following pairs of solid salts. In each case state whether a precipitate will be present, and if so what its composition is. Note: The precipitate may be either one or both of the original salts or one or more of the products formed by reaction between the salts. 3. (10 pts) a. Pb(C2H,O2)2 and NaCI b. BaSO4 and Cus c. Ni(NO3)2 and CaCl2 d. AgCl and Cu(NO3)2 e. Na CO, and MgCl2

Answer 1

3.

a.

Pb(CH₃COO)₂ + 2 NaCl $\rightarrow$ PbCl₂ + 2 CH3COONa

Both lead acetate and sodium chloride are soluble in cold water. But the product PbCl₂ is insoluble in cold water. Hence, it will precipitate out from the reaction mixture.

b.

Both BaSO₄ and CuS are insoluble in cold water. Hence, both of them will constitute the precipitate.

c.

Ni(NO₃)₂ + CaCl₂ $\rightarrow$ NiCl₂ + Ca(NO₃)₂

Neither the reactants nor the products are insoluble. Hence, no precipitate will form.

d.

AgCl is insoluble in cold water. Cu(NO₃)₂ is soluble in water. Hence, AgCl will be in the precipitate.

e.

Na₂CO₃ + MgCl₂ $\rightarrow$ MgCO₃ + 2 NaCl

Sodium carbonate, magnesium chloride and sodium chloride are soluble in water. Magnesium carbonate is insoluble in cold water. Hence, MgCO₃ will precipitate.