Chapter 15, Problem 15.7QP

(a)

Interpretation Introduction

Interpretation: Lewis structure for ${\text{HC}}_{\text{2}}{\text{O}}_{\text{4}}{}^{-}$ and ${\text{C}}_{\text{2}}{\text{O}}_{\text{4}}{}^{2-}$ has to be drawn.

Concept Introduction: Lewis dot symbol is used to represent the valence electrons of an atom or ion using dots surrounding the element symbol along four sides of the element symbol without maintaining exact order for the placement of dots.

In Lewis dot symbol representation, the symbol of element is surrounded by "dots" indicating the number of valence electrons available for the element. The dots can be placed one at a time on all the four sides, further electron can be placed by pairing up with the first placed dots.  According to the number of electrons added or removed, charge must be placed on the Lewis dot symbol for cations and anions.

The valence electron is the number of electrons present in the outermost shell of the atom. The number of valence electrons will be same for the same group elements which are represented by Lewis dot symbol.

To draw: The Lewis structure for the ${\text{HC}}_{\text{2}}{\text{O}}_{\text{4}}{}^{-}$ and ${\text{C}}_{\text{2}}{\text{O}}_{\text{4}}{}^{2-}$.

(b)

Interpretation Introduction

Concept Introduction: Bronsted's definition is based on the chemical reaction that occurs when both acids and bases are added with each other.  In Bronsted's theory acid donates proton, while base accepts proton from acid resulting in the formation of water.

Example: Consider the following reaction.

$\text{HCl}\text{+}{\text{NH}}_{\text{3}}\to {\text{NH}}_{\text{4}}{}^{\text{+}}\text{+}{\text{Cl}}^{\text{-}}$

Hydrogen chloride donates a proton, and hence it is a Bronsted acid.  Ammonia accepts a proton, and hence it is a Bronsted base.

When Bronsted base accepts a proton the protonated species is known as conjugate acid and when Bronsted acid loses a proton the deprotonated species is known as conjugate base.  The conjugated acid-base pair is present in opposite side of the reaction.  In this the base has one proton less than the acid.

To identify: The four species to be identified which can act as acid, base or both.