Chapter 6, Problem 6D.12E

(a)

Interpretation Introduction

Interpretation:

The aqueous solution of potassium oxalate salt is neutral pH or greater than 7 or less than 7 has to be determined.

Aqueous solution of salt:

The salt is added in water, it will dissolved and generate ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}\text{or}{\text{OH}}^{\text{-}}$ ions it is called hydrolysis reaction. Based on ions concentration whether the solution is acid or base as to be identified. Depends on the salts react with water it may have three possibilities to get neutral or acidic or basic nature of the solution. A salt can be either weak acid and weak base or strong acid and strong base or strong acid and weak base and strong base and weak acid.

Neutral solution:

For the neutral solution, the pH is at 7.  In periodic table, group 1 and 2 elements and from other groups those who have +1 charge cations are weak Lewis acids, these hydrated ions does not affect the protons from water.  As well as these metal cations are very big, otherwise they may have very small charge to hydrating water molecules to get appreciable polarization effect.  These types of cations are called neutral cations because they may not affect the pH of the solution.

The anions from strong acids like halides (except F), nitrates, perchlorates are such weak Lewis bases, so they may not affect the pH of the solution.  These anions are called neutral in water.

Acidic solution:

The conjugate acids of weak bases cations make the solution acidic in aqueous medium, because it acts as proton donors. In another case, the metal cations with high charge can act as Lewis acids in aqueous medium solution, even though the cations do not have protons to donate.

Basic solution:

The conjugate bases of weak acids anions make the solution basic in aqueous medium, here, the protons leaves from the negatively charged anions.

(b)

Interpretation Introduction

Interpretation:

The aqueous solution of calcium nitrate salt is neutral pH or greater than 7 or less than 7 has to be determined.

Concept introduction:

Refer to part (a).

(c)

Interpretation Introduction

Interpretation:

The aqueous solution of methylammonium hydrochloride salt is neutral pH or greater than 7 or less than 7 has to be determined.

Concept introduction:

Refer to part (a).

(d)

Interpretation Introduction

Interpretation:

The aqueous solution of potassium phosphate salt is neutral pH or greater than 7 or less than 7 has to be determined.

Concept introduction:

Refer to part (a).

(e)

Interpretation Introduction

Interpretation:

The aqueous solution of ferric chloride salt is neutral pH or greater than 7 or less than 7 has to be determined.

Concept introduction:

Refer to part (a).

(f)

Interpretation Introduction

Interpretation:

The aqueous solution of pyridinium chloride salt is neutral pH or greater than 7 or less than 7 has to be determined.

Concept introduction:

Refer to part (a).