Chapter 17, Problem 120SCQ

 (a)

Interpretation Introduction

Interpretation:

A balanced chemical equation for the preparation of ${\text{AlPO}}_{\text{4}}$ has to be written.

Concept introduction: The metals of group $\text{3A}$ form $+3$ ions because the highest oxidation number is always equal to the group number of that element. The non-metal gains these electrons to form anions with $-1$ and $-2$ charge.

The stoichiometric coefficients are multiplied with the compounds in the chemical equation to have an equal number of atoms on both sides of the equation. The equation is known as a balanced chemical equation if there are an equal number of atoms of each element in both the product and reactant side.

(b)

Interpretation Introduction

Interpretation:

The theoretical yield of ${\text{AlPO}}_{\text{4}}$ has to be calculated.

Concept introduction: Theoretical yield is the maximum amount of product that can be obtained from a chemical reaction such that one of the reactants is completely consumed called limiting reagent. The maximum amount of product formed can be predicted from the stoichiometric coefficient of the limiting reagent in the balanced chemical reaction.

 (c)

Interpretation Introduction

Interpretation:

The concentration of ${\text{Al}}^{3+}$ and ${\text{PO}}_4{}^{3-}$ at equilibrium has to be calculated.

Concept introduction:

Solubility product constant $K_{\text{sp}}$ is an equilibrium constant and is defined as the product of the equilibrium concentration of the ions of the salt raised to the power of their coefficients in the balanced chemical equation.

For example, general salt ${\text{A}}_x{\text{B}}_y$ when dissolved in water dissociates as,

  ${\text{A}}_x{\text{B}}_y\left(\text{s}\right)\rightleftharpoons x{\text{A}}^{y+}\left(\text{aq}\right)+y{\text{B}}^{-x}\left(\text{aq}\right)$

The expression for $K_{\text{sp}}$ of a salt is,

$K_{\text{sp}}={\left[{\text{A}}^{y+}\right]}^x{\left[{\text{B}}^{-x}\right]}^y$       

 (d)

Interpretation Introduction

Interpretation:

The solubility of ${\text{AlPO}}_{\text{4}}$ increase or decrease upon addition of $\text{HCl}$ to the solution has to be calculated.

Concept introduction: The solubility of insoluble salts containing anions (conjugate base of a weak acid) such as hydroxide, acetate, carbonate, phosphate and sulfide increases in the presence of strong acid than in pure water. Whereas the solubility of insoluble salts containing anions (conjugate base of a strong acid) such as chlorides decreases in the presence of strong acid than in the pure water.