Chapter 21, Problem 21.141MP

Interpretation Introduction

(a)

Interpretation:

The equilibrium equation for the reaction is to written and the reason for ${\text{CrO}}_4^{2-}$ ions to predominate in basic solutions and ${\text{Cr}}_{\text{2}}{\text{O}}_7^{2-}$ ions to predominate in acidic solution needs to be explained.

Concept introduction:

The formula that will be used −

$K_1=\frac{1}{K_w}$

Here, K₁ is the second ionization constant of the complex and $K_w$ is the ionic product of water.

Interpretation Introduction

(b)

Interpretation:

The concentration of ${\text{CrO}}_{\text{4}}^{\text{2-}}$ ions and ${\text{Cr}}_{\text{2}}{\text{O}}_{\text{7}}^{\text{2-}}$ ions are to be calculated in a solution that has a total chromium concentration of 0.100M and pH of 4.000.

Concept introduction:

The pH of the solution can be calculated as follows:

$\text{pH}=-\log [{\text{H}}^{+}]$

For a reaction in which A and B reactants combined to form AB (product) can be represented as follows:

$K_a=\frac{[Product]}{[Reactant\text{A}][Reactant\text{B}]}$

Interpretation Introduction

(c)

Interpretation:

The concentration of $Cr{O}_4^{2-}$ ions and $C{r}_2{O}_7^{2-}$ ions are to be calculated when the pH is 2.00.

Concept introduction:

The pH of the solution can be calculated as follows:

$\text{pH}=-\log [{\text{H}}^{+}]$

For a reaction in which A and B reactants combined to form AB (product) can be represented as follows:

$K_a=\frac{[Product]}{[Reactant\text{A}][Reactant\text{B}]}$