Chapter U4.18, Problem 6E

(a)

Interpretation Introduction

Interpretation:

If a particle view of Mg (OH) ₂ is drawn with 10 Mg²+ ions then the number of OH- required must be explained.

Concept Introduction :

Mg (OH) ₂ is a base which undergoes dissociation to produce one Mg²+ and 2 OH^-.

Answer to Problem 6E

20 OH- will be required.

Explanation of Solution

The dissociation of Mg (OH) ₂ can be shown as

  $\text{Mg }{\left(\text{OH}\right)}_{\text{2}}\to {\text{Mg}}^{\text{2+}}{\text{+2OH}}^{\text{-}}$

Thus, it is clear than the number of Mg²+ is half of OH- ions. So for 10 Mg²+ ions 20 OH- ions will be required.

(b)

Interpretation Introduction

Interpretation:

A particle view of Mg (OH) ₂ must be drawn with 10 Mg²+ ions.

Concept Introduction :

Number of OH- will be doubled as compared to Mg²+ as 1 Mg (OH) ₂ produces 1 Mg²+and 2 OH^-.

Answer to Problem 6E

A sketch is shown below for Mg (OH) ₂ with 10 Mg²+ ions.

Here, red dots represent Mg²+ and black dots represent OH^-.

Explanation of Solution

From the sketch it is clear that number of OH- is double as compared to Mg²⁺.For 10 red dots (Mg²⁺) there are 20 black dots (OH^-).