Question

Write the conjugate base for each of the following acids. a. \(\mathrm{HCO}_{3}\) b. \(\mathrm{HBrO}_{4}\) c. \(\mathrm{HSO}_{3}^{-}\) d. \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\)

Short answer

The conjugate bases for each of the given acids are: a. \(\mathrm{CO}_{3}^{2-}\) b. \(\mathrm{BrO}_{4}^{-}\) c. \(\mathrm{SO}_{3}^{2-}\) d. \(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}^{-}\)

Step-by-step solution

Identify the hydrogen ion to be removed

For each acid, identify the hydrogen ion (H+) that will be removed to form the conjugate base. In most cases, this will be the hydrogen atom directly bonded to the heteroatom (O, N, S, etc.) with the highest electronegativity or the one with negative charge.

Remove a hydrogen ion to form the conjugate base

Next, we will remove one H+ ion from each acid to reveal its conjugate base. a. \(\mathrm{HCO}_{3}\)

Conjugate base of \(\mathrm{HCO}_{3}\):

To form the conjugate base, remove one H+ ion: \(\mathrm{CO}_{3}^{2-}\) b. \(\mathrm{HBrO}_{4}\)

Conjugate base of \(\mathrm{HBrO}_{4}\):

To form the conjugate base, remove one H+ ion: \(\mathrm{BrO}_{4}^{-}\) c. \(\mathrm{HSO}_{3}^{-}\)

Conjugate base of \(\mathrm{HSO}_{3}^{-}\):

To form the conjugate base, remove one H+ ion: \(\mathrm{SO}_{3}^{2-}\) d. \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\)

Conjugate base of \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\):

To form the conjugate base, remove one H+ ion: \(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}^{-}\)

Key concepts

Acids and Bases

Acids and bases are fundamental concepts in chemistry that describe substances' ability to donate or accept protons (\(\text{H}^+\)").An acid is any substance that can donate a proton to another substance, while a base is one that can accept a proton.In any acid-base reaction,the acid donates a proton and becomes its conjugate base.
For example, when bicarbonate ion (\(\text{HCO}_3^-\)) acts as an acid by losing a proton,it forms the carbonate ion (\(\text{CO}_3^{2-}\)), which is its conjugate base.
Acids and bases can also be categorized by their strength, which refers to the degree to which they ionize in water.Strong acids and bases ionize completely,whereas weak acids and bases only partially ionize.This concept is essential when predicting the behavior of substances in solution.

Chemical Equilibrium

Chemical equilibrium is a state in a reversible chemical reaction where the rates of the forward and reverse reactions are equal.At equilibrium, the concentration of reactants and products remains constant,but they are not necessarily equal.
For acid-base reactions, equilibrium is crucial to understanding how conjugate acids and bases behave in solution.For example, the equilibrium between acetic acid (\(\text{HC}_2\text{H}_3\text{O}_2\)) and its conjugate base (acetate ion, \(\text{C}_2\text{H}_3\text{O}_2^-\)) will depend on the reaction conditions.

• When more acetic acid ionizes, the concentration of acetate ions increases, shifting the equilibrium.
• Changing the concentration of either species will shift the equilibrium position,an example of Le Chatelier's Principle.

Equilibrium concepts are fundamental in predicting the extent of acid-base reactions and their resulting products.

Ionization

Ionization refers to the process where an atom or molecule gains or loses an electron,forming ions.In the context of acids and bases, ionization typically involves the loss or gain of a proton (\(\text{H}^+\)).
For instance, when hydrogen bromate (\(\text{HBrO}_4\)) ionizes, it loses a hydrogen ion to become bromate ion (\(\text{BrO}_4^-\)), its conjugate base.This loss of a proton is typical of acid ionization,which plays an essential role in acid-base reactions.
Several factors influence the extent of ionization:

• Strength of the acid or base: Strong acids completely ionize in solution, whereas weak acids only partially do.
• Polarity of the bond: The more polar the bond to the hydrogen, the easier it is for the molecule to lose a proton.

Understanding ionization is critical for predicting how substances will behave in chemical reactions and in determining the pH of solutions.