Q22.58CP - Chemistry: Molecular Nature Of Matter And Change

Question

Heavy water ${\mathbf{\text{D}}}_{\mathbf{\text{2}}}\mathbf{\text{O}}$ is used to make deuterated chemicals. 

(a) What major species, aside from the starting compounds, do you expect to find in a solution of  ${\mathbf{\text{CH}}}_{\mathbf{\text{3}}}\mathbf{\text{OH}}$ and  ${\mathbf{\text{D}}}_{\mathbf{\text{2}}}\mathbf{\text{O}}$? 

(b) Write equations to explain how these various species arise. (Hint: Consider the autoionization of both components.)

Step-by-Step Solution

Answer

 

(a) We can anticipate the presence of species such as: ${\text{CH}}_3\text{OD}$,

         ${\text{D - O - H,OD}}^{\text{ - }}{\text{,CH}}_{\text{3}}{\text{O}}^{\text{ - }}{\text{D}}_{\text{3}}{\text{O}}^{\text{ + }}{\text{,HD}}_{\text{2}}{\text{O}}^{\text{ + }}\text{. }$

 (b) The required equations are:

 $$\begin{gathered} {\text{2D}}_{\text{2}}\text{O}\to {\text{D}}_{\text{3}}{\text{O}}^{\text{ + }}{\text{ + OD}}^{\text{ - }} \\ {\text{CH}}_{\text{3}}{\text{OH + D}}_{\text{2}}\text{O}\to {\text{CH}}_{\text{3}}\text{OD + D - O - H} \\ {\text{CH}}_{\text{3}}{\text{OH + D}}_{\text{2}}\text{O}\to {\text{CH}}_{\text{3}}{\text{O}}^{\text{ - }}{\text{ + HD}}_{\text{2}}{\text{O}}^{\text{ + }} \end{gathered}$$

Step 1: Definition of Elements in nature and Industry

Chemically, elements are substances that cannot be broken down into simpler things. Hydrogen (H), with an atomic number of 1, is one of nature's elements. This element gave origin to all others and makes up 75% of the mass of the cosmos. Carbon (C) is a six-atomic element.

Step 2: What major species, aside from the starting compounds

(a)

 

Even though deuterium ions are less active than hydrogen ions (remember the kinetic isotope effect), processes like autoionization and $\text{H/D}$ exchange will occur in a solution containing  ${\text{CH}}_{\text{3}}\text{OH}$ and  ${\text{D}}_{\text{2}}\text{O}$.

As a result, we can anticipate the presence of species such as: ${\text{CH}}_3\text{OD}$,

 ${\text{D - O - H,OD}}^{\text{ - }}{\text{,CH}}_{\text{3}}{\text{O}}^{\text{ - }}{\text{D}}_{\text{3}}{\text{O}}^{\text{ + }}{\text{,HD}}_{\text{2}}{\text{O}}^{\text{ + }}\text{. }$

Step 3: Write equations to explain how these various species arise

(b) 

 

The chemicals equations that describe the processes mentioned above are:

 

$$\begin{gathered} {\text{2D}}_{\text{2}}\text{O}\to {\text{D}}_{\text{3}}{\text{O}}^{\text{ + }}{\text{ + OD}}^{\text{ - }} \\ {\text{CH}}_{\text{3}}{\text{OH + D}}_{\text{2}}\text{O}\to {\text{CH}}_{\text{3}}\text{OD + D - O - H} \\ {\text{CH}}_{\text{3}}{\text{OH + D}}_{\text{2}}\text{O}\to {\text{CH}}_{\text{3}}{\text{O}}^{\text{ - }}{\text{ + HD}}_{\text{2}}{\text{O}}^{\text{ + }} \end{gathered}$$