Predict whether aqueous solutions of the following...

Predict whether aqueous solutions of the following subsstances are acidic, basic, or neutral: $(\mathbf{a})\mathrm{AlCl}_{3},$ $(\mathbf{b})\mathrm{NaBr}$ $(\mathbf{c}) \mathrm{NaClO},(\mathbf{d})\left[\mathrm{CH}_{3} \mathrm{NH}_{3}\right] \mathrm{NO}_{3},(\mathbf{e}) \mathrm{Na}_{2} \mathrm{SO}_{3}$

Key Concepts

Salts Hydrolysis

Salts hydrolysis is the reaction of dissolved salt ions with water, which can lead to the production of either hydrogen ions (H+) or hydroxide ions (OH–) in solution. The outcome depends on the relative strengths of the parent acid and base; salts from strong acids and strong bases tend to be neutral, while those from weak acids or bases may display acidic or basic characteristics.

Hydrolysis of Metal Cations

Metal cations, particularly those with high charge density such as Al3+, can undergo hydrolysis in water. This process involves the cation interacting with water molecules to produce hydronium ions (H3O+) or free hydrogen ions (H+), leading to an acidic solution.

Conjugate Base Behavior

Ions derived from the conjugate base of a weak acid, like ClO–, have a tendency to react with water by accepting a proton, which generates hydroxide ions (OH–) and results in a basic solution.

Conjugate Acid Behavior

Ions originating from the conjugate acid of a weak base, such as methylammonium (CH3NH3+), can donate a proton to water. This leads to an increase in hydrogen ion concentration, making the solution acidic.

Neutral Salt Formation

When a salt is formed from a strong acid and a strong base, like NaBr, neither ion undergoes significant hydrolysis. As a result, the solution remains neutral because there is no formation of excess H+ or OH– ions.

Transcript

00:01 Chapter 16, problem 84, from the textbook chemistry, the central science.

00:09 So the question's asking us to predict whether the solution is either basic, acidic, or neutral.

00:15 So what we're going to do is we're going to take the solution and break it into ions and then determine if each of the ions are either basic or acidic.

00:27 And that will help determine which is the overall, which is the overall condition of the solution.

00:40 So for a, we have al, cl3, and whenever you break it down, you have al3 plus and cl minus.

00:52 We know that cl minus is the conjugate base for a very strong acid of hcl.

01:07 So this is very acidic.

01:10 And al3 plus is also acidic.

01:14 Usually ions that have a plus three charge are acidic.

01:22 So we have two things that are acidic.

01:24 So the overall solution is going to be acidic.

01:30 So b.

01:34 We have n -a -b -r.

01:38 So we have n -a -plus, n -b -r -minus.

01:46 First, we know that n -a -plus is a conjugate acid for n -a -o -h, n -b -r -minus is a conjugate base for hbr.