1.a) What did you observe upon the addition of NH3 (aq) to the magnesium chloride solution? Explain using relevant chemical reactions.

I observed a colorless liquid. (Not sure how to explain)

b) What happens when NH4Cl was added? Explain observation with respect to the equilibrium reactions that exist in the test tube using any relevant chemical reactions.

I observed a clear liquid (no change)
Not sure how to explain.

I appreciate the help!

Mg(OH)2 ==> Mg^2+ + 2OH^-

Ksp = (Mg^2+)(OH^-)^2

When NH3 is added to the solution of MgCl2 (which is quite soluble) the NH3 reacts with the H2O to form NH4^+ + OH^-.
That increases the OH^- enough to form a Mg(OH)2 ppt because Ksp for Mg(OH)2 is exceeded. (SO YOU SHOULD HAVE OBSERVED A WHITE PPT AT THAT POINT. THE FACT YOU DIDN'T MEANS YOU DIDN'T ADD ENOUGH NH3.)
NH3 + HOH ==> NH4^ + OH^-

Then when you add NH4Cl, that increases the NH4^+ from the NH3 solution, the NH3 equilibrium is shifted to the left which decreases the OH^- to the point that the Ksp for Mg(OH)2 is no longer exceeded. As a result the Mg(OH)2 ppt that was there dissolves. This is the chemistry behind the qualitative separation of group III cations (Al, Fe, Cr, etc) from group V cations (Mg especially). If not for the addition of NH4Cl, Mg from group V ppts in group III. So you get a ppt in group III, it doesn't pan out to be anything so you use the eenie, meenie, miney, mo method and over report some metal in group III. Then when you get to group V, you under report Mg since all of it pptd earlier.

a) When NH3 (aq) is added to a magnesium chloride solution, a white precipitate is formed. This is due to the reaction between ammonium hydroxide (NH3) and magnesium chloride (MgCl2) to form magnesium hydroxide (Mg(OH)2), which is insoluble and precipitates out:

MgCl2 (aq) + 2NH3 (aq) → Mg(OH)2 (s) + 2NH4Cl (aq)

The precipitate, magnesium hydroxide, appears as a white solid in the solution.

b) When NH4Cl is added to the solution, there is no observable change. This is because NH4Cl does not react with magnesium hydroxide. However, it is important to note that a reaction does occur according to the equilibrium reactions that exist in the test tube. The reactions involved include the dissociation of ammonium chloride (NH4Cl) into ammonium (NH4+) and chloride (Cl-) ions:

NH4Cl (aq) → NH4+ (aq) + Cl- (aq)

Since there is no reaction with magnesium hydroxide, the solution remains clear after the addition of NH4Cl, indicating that no new solid precipitate is formed.

To explain the observations upon the addition of NH3 (aq) to the magnesium chloride solution, we need to understand the relevant chemical reactions involved:

a) When NH3 (aq) is added to the magnesium chloride solution (MgCl2 (aq)), chemical reactions occur. The reaction can be represented as follows:

MgCl2 (aq) + 2NH3 (aq) → Mg(NH3)2Cl2 (aq)

In this reaction, the ammonia (NH3) molecules bond with the magnesium (Mg) and chloride (Cl) ions, forming magnesium ammine chloride complex ions (Mg(NH3)2Cl2). These complex ions are responsible for the colorless appearance of the resulting liquid.

b) When NH4Cl is added to the solution, no noticeable change is observed. This is because NH4Cl does not undergo a significant chemical reaction with the components of the solution. It remains as NH4Cl, which is a soluble compound in water and does not contribute to any change in appearance.

Overall, the addition of ammonia (NH3) forms complex ions with the magnesium chloride solution, leading to a colorless liquid. However, the addition of NH4Cl does not cause any visible change in the appearance of the solution.