Question

Part 1: (a) Which of the following reactions will produce a precipitate? CuSO4(aq) + Fe(NO3)2(aq) → Kl(aq) + Zn(NO3)2(aq) - NaOH(aq) + MgCl2(aq) → NaOH(aq) + KNO3(aq) + Part 2 out of 2 (b) Write the net ionic equation for the precipitation reaction in Part A. Remember to include the proper physical states and charges of ions. When writing ions, if a charge number is not "l", place the charge number before the charge sign. If a charge number is "1", do not include the charge number in the formula.

Answer 1

A) yes 3rd option is the correct option.

It goes like this:

First, we add NaOH and MgCl₂ solids to the water. And both of them are soluble and dissociates into respective ions.

NaOH(s)  $\rightarrow$ NaOH(aq)  $\rightarrow$ Na⁺ (aq) + OH^- (aq)  

MgCl₂ (s) $\rightarrow$ MgCl₂ (aq) $\rightarrow$   Mg²⁺ (aq) + 2Cl^-(aq)

But what about the anion of one salt and cation of the other. They may form a salt which is insoluble in water. Then the salt will precipitate out. And here, Mg(OH)₂ (s) is insoluble in water.

So it will precipitate out. Mg²⁺ (aq) + 2OH^-(aq)  $\rightarrow$  Mg(OH)₂ (s), and this the answer for part B.